diff --git a/docs/conf.py b/docs/conf.py
index bcd2ee8..747bdaa 100755
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -18,11 +18,11 @@
 # relative to the documentation root, use os.path.abspath to make it
 # absolute, like shown here.
 #
+import facho
 import os
 import sys
 sys.path.insert(0, os.path.abspath('..'))
 
-import facho
 
 # -- General configuration ---------------------------------------------
 
diff --git a/examples/generate-invoice-from-cli.py b/examples/generate-invoice-from-cli.py
index a2d6351..b53f9f2 100644
--- a/examples/generate-invoice-from-cli.py
+++ b/examples/generate-invoice-from-cli.py
@@ -11,13 +11,18 @@ from facho.fe import form_xml
 from facho.fe import fe
 
 # importar otras necesarias
-from datetime import datetime, date
+from datetime import datetime
 
 # Datos del fomulario del SET de pruebas
-INVOICE_AUTHORIZATION = '181360000001'  # Número suministrado por la Dian en el momento de la creación del SET de Pruebas
-ID_SOFTWARE = '57bcb6d1-c591-5a90-b80a-cb030ec91440' #Id suministrado por la Dian en el momento de la creación del SET de Pruebas  
-PIN = '19642' #Número creado por la empresa para poder crear el SET de pruebas
-CLAVE_TECNICA = 'fc9eac422eba16e21ffd8c5f94b3f30a6e38162d' ##Id suministrado por la Dian en el momento de la creación del SET de Pruebas  
+# Número suministrado por la Dian en el momento de la creación del SET de
+# Pruebas
+INVOICE_AUTHORIZATION = '181360000001'
+# Id suministrado por la Dian en el momento de la creación del SET de Pruebas
+ID_SOFTWARE = '57bcb6d1-c591-5a90-b80a-cb030ec91440'
+# Número creado por la empresa para poder crear el SET de pruebas
+PIN = '19642'
+# Id suministrado por la Dian en el momento de la creación del SET de Pruebas
+CLAVE_TECNICA = 'fc9eac422eba16e21ffd8c5f94b3f30a6e38162d'
 
 
 # callback que retonar las extensiones XML necesarias
@@ -26,15 +31,24 @@ CLAVE_TECNICA = 'fc9eac422eba16e21ffd8c5f94b3f30a6e38162d' ##Id suministrado por
 # muchos de los valores usados son obtenidos
 # del servicio web de la DIAN.
 def extensions(inv):
-    security_code = fe.DianXMLExtensionSoftwareSecurityCode(ID_SOFTWARE, PIN, inv.invoice_ident)
+    security_code = fe.DianXMLExtensionSoftwareSecurityCode(
+        ID_SOFTWARE, PIN, inv.invoice_ident)
     authorization_provider = fe.DianXMLExtensionAuthorizationProvider()
     cufe = fe.DianXMLExtensionCUFE(inv, CLAVE_TECNICA, fe.AMBIENTE_PRUEBAS)
-    software_provider = fe.DianXMLExtensionSoftwareProvider('nit_empresa', 'dígito_verificación', ID_SOFTWARE)
-    inv_authorization = fe.DianXMLExtensionInvoiceAuthorization(INVOICE_AUTHORIZATION,
-                                                                datetime(2019, 1, 19),#Datos toamdos de 
-                                                                datetime(2030, 1, 19),#la configuración 
-                                                                'SETP', 990000000, 995000000)#del SET de pruebas
-    return [security_code, authorization_provider, cufe, software_provider, inv_authorization]
+    software_provider = fe.DianXMLExtensionSoftwareProvider(
+        'nit_empresa', 'dígito_verificación', ID_SOFTWARE)
+    inv_authorization = fe.DianXMLExtensionInvoiceAuthorization(
+        INVOICE_AUTHORIZATION,
+        # Datos tomados de la configuración
+        datetime(2019, 1, 19),
+        datetime(2030, 1, 19),
+        'SETP', 990000000, 995000000)  # del SET de pruebas
+    return [
+        security_code,
+        authorization_provider,
+        cufe,
+        software_provider,
+        inv_authorization]
 
 
 def invoice():
@@ -49,7 +63,7 @@ def invoice():
     # asignar tipo de operacion ver DIAN:6.1.5
     inv.set_operation_type('10')
     inv.set_supplier(form.Party(
-        legal_name = 'Nombre registrado de la empresa',
+        legal_name='Nombre registrado de la empresa',
         name='Nombre comercial o él mismo nombre registrado',
         ident=form.PartyIdentification(
             'nit_empresa', 'digito_verificación', '31'),
@@ -65,22 +79,22 @@ def invoice():
             form.Country('CO', 'Colombia'),
             form.CountrySubentity('05', 'Antioquia')),
     ))
-    #Tercero a quien se le factura
+    # Tercero a quien se le factura
     inv.set_customer(form.Party(
-        legal_name = 'consumidor final',
-        name = 'consumidor final',
-        ident = form.PartyIdentification('222222222222', '', '13'),
-        responsability_code = form.Responsability(['R-99-PN']),
-        responsability_regime_code = '49',
-        organization_code = '2',
-        email = "consumidor_final0final.final",
-        address = form.Address(
+        legal_name='consumidor final',
+        name='consumidor final',
+        ident=form.PartyIdentification('222222222222', '', '13'),
+        responsability_code=form.Responsability(['R-99-PN']),
+        responsability_regime_code='49',
+        organization_code='2',
+        email="consumidor_final0final.final",
+        address=form.Address(
             '', '', form.City('05001', 'Medellín'),
             form.Country('CO', 'Colombia'),
             form.CountrySubentity('05', 'Antioquia')),
         #  tax_scheme = form.TaxScheme('01', 'IVA')
     ))
-    # asignar metodo de pago    
+    # asignar metodo de pago
     inv.set_payment_mean(form.PaymentMean(
         # metodo de pago ver DIAN:3.4.1
         id='1',
diff --git a/examples/generate-nomina-from-cli.py b/examples/generate-nomina-from-cli.py
index 05fccbe..41e8dd5 100644
--- a/examples/generate-nomina-from-cli.py
+++ b/examples/generate-nomina-from-cli.py
@@ -1,26 +1,28 @@
 
 from facho import fe
 
+
 def extensions(nomina):
     return []
 
+
 def nomina():
     nomina = fe.nomina.DIANNominaIndividual()
 
     nomina.asignar_metadata(fe.nomina.Metadata(
         secuencia=fe.nomina.NumeroSecuencia(
-            numero = 'N00001',
+            numero='N00001',
             consecutivo=232
         ),
         lugar_generacion=fe.nomina.Lugar(
-            pais = fe.nomina.Pais(
-                code = 'CO'
+            pais=fe.nomina.Pais(
+                code='CO'
             ),
-            departamento = fe.nomina.Departamento(
-                code = '05'
+            departamento=fe.nomina.Departamento(
+                code='05'
             ),
-            municipio = fe.nomina.Municipio(
-                code = '05001'
+            municipio=fe.nomina.Municipio(
+                code='05001'
             ),
         ),
         proveedor=fe.nomina.Proveedor(
@@ -32,62 +34,62 @@ def nomina():
     ))
 
     nomina.asignar_informacion_general(fe.nomina.InformacionGeneral(
-        fecha_generacion = '2020-01-16',
-        hora_generacion = '1053:10-05:00',
-        tipo_ambiente = fe.nomina.InformacionGeneral.AMBIENTE_PRODUCCION,
-        software_pin = '693',
-        periodo_nomina = fe.nomina.PeriodoNomina(code='1'),
-        tipo_moneda = fe.nomina.TipoMoneda(code='COP')
+        fecha_generacion='2020-01-16',
+        hora_generacion='1053:10-05:00',
+        tipo_ambiente=fe.nomina.InformacionGeneral.AMBIENTE_PRODUCCION,
+        software_pin='693',
+        periodo_nomina=fe.nomina.PeriodoNomina(code='1'),
+        tipo_moneda=fe.nomina.TipoMoneda(code='COP')
     ))
 
     nomina.asignar_empleador(fe.nomina.Empleador(
-        nit = '700085371',
-        dv = '1',
-        pais = fe.nomina.Pais(
-            code = 'CO'
+        nit='700085371',
+        dv='1',
+        pais=fe.nomina.Pais(
+            code='CO'
         ),
-        departamento = fe.nomina.Departamento(
-            code = '05'
+        departamento=fe.nomina.Departamento(
+            code='05'
         ),
-        municipio = fe.nomina.Municipio(
-            code = '05001'
+        municipio=fe.nomina.Municipio(
+            code='05001'
         ),
-        direccion = 'calle etrivial'
+        direccion='calle etrivial'
     ))
 
     nomina.asignar_trabajador(fe.nomina.Trabajador(
-        tipo_contrato = fe.nomina.TipoContrato(
-            code = '1'
+        tipo_contrato=fe.nomina.TipoContrato(
+            code='1'
         ),
-        alto_riesgo = False,
-        tipo_documento = fe.nomina.TipoDocumento(
-            code = '11'
+        alto_riesgo=False,
+        tipo_documento=fe.nomina.TipoDocumento(
+            code='11'
         ),
-        primer_apellido = 'gnu',
-        segundo_apellido = 'emacs',
-        primer_nombre = 'facho',
-        lugar_trabajo = fe.nomina.LugarTrabajo(
-            pais = fe.nomina.Pais(code='CO'),
-            departamento = fe.nomina.Departamento(code='05'),
-            municipio = fe.nomina.Municipio(code='05001'),
-            direccion = 'calle facho'
+        primer_apellido='gnu',
+        segundo_apellido='emacs',
+        primer_nombre='facho',
+        lugar_trabajo=fe.nomina.LugarTrabajo(
+            pais=fe.nomina.Pais(code='CO'),
+            departamento=fe.nomina.Departamento(code='05'),
+            municipio=fe.nomina.Municipio(code='05001'),
+            direccion='calle facho'
         ),
-        numero_documento = '800199436',
-        tipo = fe.nomina.TipoTrabajador(
-            code = '01'
+        numero_documento='800199436',
+        tipo=fe.nomina.TipoTrabajador(
+            code='01'
         ),
-        salario_integral = True,
-        sueldo = fe.nomina.Amount(1_500_000)
+        salario_integral=True,
+        sueldo=fe.nomina.Amount(1_500_000)
     ))
 
     nomina.adicionar_devengado(fe.nomina.DevengadoBasico(
-        dias_trabajados = 60,
-        sueldo_trabajado = fe.nomina.Amount(3_500_000)
+        dias_trabajados=60,
+        sueldo_trabajado=fe.nomina.Amount(3_500_000)
     ))
 
     nomina.adicionar_deduccion(fe.nomina.DeduccionSalud(
-        porcentaje = fe.nomina.Amount(19),
-        deduccion = fe.nomina.Amount(1_000_000)
+        porcentaje=fe.nomina.Amount(19),
+        deduccion=fe.nomina.Amount(1_000_000)
     ))
 
     return nomina
diff --git a/tests/fixtures.py b/tests/fixtures.py
index 574e3ac..8b32db6 100644
--- a/tests/fixtures.py
+++ b/tests/fixtures.py
@@ -2,6 +2,7 @@ import pytest
 import facho.fe.form as form
 from datetime import datetime
 
+
 @pytest.fixture
 def simple_debit_note_without_lines():
     inv = form.DebitNote(form.InvoiceDocumentReference(
@@ -15,7 +16,7 @@ def simple_debit_note_without_lines():
     inv.set_supplier(form.Party(
         name='facho-supplier',
         ident=form.PartyIdentification('123', '', '31'),
-        responsability_code = form.Responsability(['ZZ']),
+        responsability_code=form.Responsability(['ZZ']),
         responsability_regime_code='48',
         organization_code='1',
         address=form.Address(
@@ -36,38 +37,47 @@ def simple_debit_note_without_lines():
     ))
     return inv
 
+
 @pytest.fixture
 def simple_credit_note_without_lines():
-    inv = form.CreditNote(form.InvoiceDocumentReference('1234', 'xx', datetime.now()))
+    inv = form.CreditNote(
+        form.InvoiceDocumentReference(
+            '1234', 'xx', datetime.now()))
     inv.set_period(datetime.now(), datetime.now())
     inv.set_issue(datetime.now())
     inv.set_ident('ABC123')
     inv.set_operation_type('20')
-    inv.set_payment_mean(form.PaymentMean(form.PaymentMean.DEBIT, '41', datetime.now(), '1234'))
+    inv.set_payment_mean(
+        form.PaymentMean(
+            form.PaymentMean.DEBIT,
+            '41',
+            datetime.now(),
+            '1234'))
     inv.set_supplier(form.Party(
-        name = 'facho-supplier',
-        ident = form.PartyIdentification('123','', '31'),
-        responsability_code = form.Responsability(['ZZ']),
-        responsability_regime_code = '48',
-        organization_code = '1',
-        address = form.Address(
+        name='facho-supplier',
+        ident=form.PartyIdentification('123', '', '31'),
+        responsability_code=form.Responsability(['ZZ']),
+        responsability_regime_code='48',
+        organization_code='1',
+        address=form.Address(
             '', '', form.City('05001', 'Medellín'),
             form.Country('CO', 'Colombia'),
             form.CountrySubentity('05', 'Antioquia'))
     ))
     inv.set_customer(form.Party(
-        name = 'facho-customer',
-        ident = form.PartyIdentification('321', '', '31'),
-        responsability_code = form.Responsability(['ZZ']),
-        responsability_regime_code = '48',
-        organization_code = '1',
-        address = form.Address(
+        name='facho-customer',
+        ident=form.PartyIdentification('321', '', '31'),
+        responsability_code=form.Responsability(['ZZ']),
+        responsability_regime_code='48',
+        organization_code='1',
+        address=form.Address(
             '', '', form.City('05001', 'Medellín'),
             form.Country('CO', 'Colombia'),
             form.CountrySubentity('05', 'Antioquia'))
     ))
     return inv
 
+
 @pytest.fixture
 def simple_invoice_without_lines():
     inv = form.NationalSalesInvoice()
@@ -75,25 +85,30 @@ def simple_invoice_without_lines():
     inv.set_issue(datetime.now())
     inv.set_ident('ABC123')
     inv.set_operation_type('10')
-    inv.set_payment_mean(form.PaymentMean(form.PaymentMean.DEBIT, '41', datetime.now(), '1234'))
+    inv.set_payment_mean(
+        form.PaymentMean(
+            form.PaymentMean.DEBIT,
+            '41',
+            datetime.now(),
+            '1234'))
     inv.set_supplier(form.Party(
-        name = 'facho-supplier',
-        ident = form.PartyIdentification('123','', '31'),
-        responsability_code = form.Responsability(['ZZ']),
-        responsability_regime_code = '48',
-        organization_code = '1',
-        address = form.Address(
+        name='facho-supplier',
+        ident=form.PartyIdentification('123', '', '31'),
+        responsability_code=form.Responsability(['ZZ']),
+        responsability_regime_code='48',
+        organization_code='1',
+        address=form.Address(
             '', '', form.City('05001', 'Medellín'),
             form.Country('CO', 'Colombia'),
             form.CountrySubentity('05', 'Antioquia'))
     ))
     inv.set_customer(form.Party(
-        name = 'facho-customer',
-        ident = form.PartyIdentification('321', '', '31'),
-        responsability_code = form.Responsability(['ZZ']),
-        responsability_regime_code = '48',
-        organization_code = '1',
-        address = form.Address(
+        name='facho-customer',
+        ident=form.PartyIdentification('321', '', '31'),
+        responsability_code=form.Responsability(['ZZ']),
+        responsability_regime_code='48',
+        organization_code='1',
+        address=form.Address(
             '', '', form.City('05001', 'Medellín'),
             form.Country('CO', 'Colombia'),
             form.CountrySubentity('05', 'Antioquia'))
@@ -108,25 +123,30 @@ def simple_invoice():
     inv.set_issue(datetime.now())
     inv.set_ident('ABC123')
     inv.set_operation_type('10')
-    inv.set_payment_mean(form.PaymentMean(form.PaymentMean.DEBIT, '41', datetime.now(), ' 1234'))
+    inv.set_payment_mean(
+        form.PaymentMean(
+            form.PaymentMean.DEBIT,
+            '41',
+            datetime.now(),
+            ' 1234'))
     inv.set_supplier(form.Party(
-        name = 'facho-supplier',
-        ident = form.PartyIdentification('123','', '31'),
-        responsability_code = form.Responsability(['ZZ']),
-        responsability_regime_code = '48',
-        organization_code = '1',
-        address = form.Address(
+        name='facho-supplier',
+        ident=form.PartyIdentification('123', '', '31'),
+        responsability_code=form.Responsability(['ZZ']),
+        responsability_regime_code='48',
+        organization_code='1',
+        address=form.Address(
             '', '', form.City('05001', 'Medellín'),
             form.Country('CO', 'Colombia'),
             form.CountrySubentity('05', 'Antioquia'))
     ))
     inv.set_customer(form.Party(
-        name = 'facho-customer',
-        ident = form.PartyIdentification('321','', '31'),
-        responsability_code = form.Responsability(['ZZ']),
-        responsability_regime_code = '48',
-        organization_code = '1',
-        address = form.Address(
+        name='facho-customer',
+        ident=form.PartyIdentification('321', '', '31'),
+        responsability_code=form.Responsability(['ZZ']),
+        responsability_regime_code='48',
+        organization_code='1',
+        address=form.Address(
             '', '', form.City('05001', 'Medellín'),
             form.Country('CO', 'Colombia'),
             form.CountrySubentity('05', 'Antioquia'))
@@ -136,7 +156,7 @@ def simple_invoice():
         quantity=form.Quantity(1, '94'),
         description='productofacho',
         item=form.StandardItem(9999),
-        price=form.Price(form.Amount(100.0),'01',''),
+        price=form.Price(form.Amount(100.0), '01', ''),
         tax=form.TaxTotal(
             tax_amount=form.Amount(0.0),
             taxable_amount=form.Amount(0.0),
diff --git a/tests/test_amount.py b/tests/test_amount.py
index b95cf8d..f8fbf5c 100644
--- a/tests/test_amount.py
+++ b/tests/test_amount.py
@@ -14,6 +14,7 @@ def test_amount_positive():
     with pytest.raises(ValueError):
         form.Amount(-1.0)
 
+
 def test_amount_equals():
     price1 = form.Amount(110.0)
     price2 = form.Amount(100 + 10.0)
@@ -22,6 +23,7 @@ def test_amount_equals():
     assert price1 == form.Amount(10) * form.Amount(10) + form.Amount(10)
     assert form.Amount(110) == (form.Amount(1.10) * form.Amount(100))
 
+
 def test_round_half_even():
     # https://www.w3.org/TR/xpath-functions-31/#func-round-half-to-even
     assert form.Amount(0.5).round(0).float() == 0.0
@@ -30,16 +32,20 @@ def test_round_half_even():
     assert form.Amount(3.567812e+3).round(2).float() == 3567.81e0
     assert form.Amount(4.7564e-3).round(2).float() == 0.0e0
 
+
 def test_round():
     # Entre 0 y 5 Mantener el dígito menos significativo
     assert form.Amount(1.133).round(2) == form.Amount(1.13)
     # Entre 6 y 9 Incrementar el dígito menos significativo
     assert form.Amount(1.166).round(2) == form.Amount(1.17)
-    # 5, y el segundo dígito siguiente al dígito menos significativo es cero o par Mantener el dígito menos significativo
+    # 5, y el segundo dígito siguiente al dígito menos significativo es cero o
+    # par Mantener el dígito menos significativo
     assert str(form.Amount(1.1542).round(2)) == str(form.Amount(1.15))
-    # 5, y el segundo dígito siguiente al dígito menos significativo es impar Incrementar el dígito menos significativo
+    # 5, y el segundo dígito siguiente al dígito menos significativo es impar
+    # Incrementar el dígito menos significativo
     assert str(form.Amount(1.1563).round(2)) == str(form.Amount(1.16))
 
+
 def test_amount_truncate():
     assert form.Amount(1.1569).truncate_as_string(2) == '1.15'
     assert form.Amount(587.0700).truncate_as_string(2) == '587.07'
@@ -49,5 +55,6 @@ def test_amount_truncate():
     assert form.Amount(10000.02245).truncate_as_string(2) == '10000.02'
     assert form.Amount(10000.02357).truncate_as_string(2) == '10000.02'
 
+
 def test_amount_format():
-    assert str(round(form.Amount(1.1569),2)) == '1.16'
+    assert str(round(form.Amount(1.1569), 2)) == '1.16'
diff --git a/tests/test_client_dian.py b/tests/test_client_dian.py
index 5b9a816..ab3309b 100644
--- a/tests/test_client_dian.py
+++ b/tests/test_client_dian.py
@@ -4,12 +4,7 @@
 # this repository contains the full copyright notices and license terms.
 
 from facho.fe.client import dian
-from facho import facho
 
-import pytest
-
-
-from datetime import datetime
 
 class FakeDianClient(dian.DianClient):
     def __init__(self, username, password, resp):
diff --git a/tests/test_facho.py b/tests/test_facho.py
index 765b894..4ac764c 100644
--- a/tests/test_facho.py
+++ b/tests/test_facho.py
@@ -7,10 +7,10 @@
 
 import pytest
 
-#from click.testing import CliRunner
+# from click.testing import CliRunner
 
 from facho import facho
-#from facho import cli
+# from facho import cli
 
 
 def test_facho_xml():
@@ -20,18 +20,19 @@ def test_facho_xml():
     invoice.text = 'Test'
     assert xml.tostring() == '<root><Invoice>Test</Invoice></root>'
 
-    invoice_line = xml.find_or_create_element('/root/Invoice/Line')
+    xml.find_or_create_element('/root/Invoice/Line')
     assert xml.tostring() == '<root><Invoice>Test<Line/></Invoice></root>'
 
 
 def test_facho_xml_with_attr():
     xml = facho.FachoXML('root')
-    invoice = xml.find_or_create_element('/root/Invoice[id=123]')
+    xml.find_or_create_element('/root/Invoice[id=123]')
     assert xml.tostring() == '<root><Invoice id="123"/></root>'
 
+
 def test_facho_xml_idempotent():
     xml = facho.FachoXML('root')
-    invoice = xml.find_or_create_element('/root/Invoice')
+    xml.find_or_create_element('/root/Invoice')
     assert xml.tostring() == '<root><Invoice/></root>'
 
     xml.find_or_create_element('/root/Invoice')
@@ -46,6 +47,7 @@ def test_facho_xml_idempotent():
     xml.find_or_create_element('/root/Invoice/Line')
     assert xml.tostring() == '<root><Invoice><Line/></Invoice></root>'
 
+
 def test_facho_xml_aliases():
     xml = facho.FachoXML('root')
     xml.register_alias_xpath('Invoice', '/root/Invoice')
@@ -54,31 +56,42 @@ def test_facho_xml_aliases():
     invoice.text = 'Test'
     assert xml.tostring() == '<root><Invoice>Test</Invoice></root>'
 
+
 def test_facho_xmlns():
     xml = facho.FachoXML('root', nsmap={
         'ext': 'https://ext',
         'sts': 'https://sts',
     })
 
-    invoiceAuthorization = xml.find_or_create_element('/root/ext:UBLExtensions/ext:UBLExtension/'
-                                         'ext:ExtensionContent/sts:DianExtensions/'
-                                         'sts:InvoiceControl/sts:InvoiceAuthorization')
-    assert xml.tostring().strip() == '<root xmlns:ext="https://ext" xmlns:sts="https://sts"><ext:UBLExtensions>'\
-        '<ext:UBLExtension>'\
-        '<ext:ExtensionContent>'\
-        '<sts:DianExtensions>'\
-        '<sts:InvoiceControl>'\
-        '<sts:InvoiceAuthorization/>'\
-        '</sts:InvoiceControl></sts:DianExtensions></ext:ExtensionContent></ext:UBLExtension></ext:UBLExtensions></root>'
+    invoiceAuthorization = xml.find_or_create_element(
+        '/root/ext:UBLExtensions/ext:UBLExtension/'
+        'ext:ExtensionContent/sts:DianExtensions/'
+        'sts:InvoiceControl/sts:InvoiceAuthorization')
+    assert xml.tostring().strip() == (
+        '<root xmlns:ext="https://ext" xmlns:sts="https://sts">'
+        '<ext:UBLExtensions>'
+        '<ext:UBLExtension>'
+        '<ext:ExtensionContent>'
+        '<sts:DianExtensions>'
+        '<sts:InvoiceControl>'
+        '<sts:InvoiceAuthorization/>'
+        '</sts:InvoiceControl></sts:DianExtensions>'
+        '</ext:ExtensionContent></ext:UBLExtension>'
+        '</ext:UBLExtensions></root>')
 
     invoiceAuthorization.text = '123456789'
-    assert xml.tostring().strip() == '<root xmlns:ext="https://ext" xmlns:sts="https://sts"><ext:UBLExtensions>'\
-        '<ext:UBLExtension>'\
-        '<ext:ExtensionContent>'\
-        '<sts:DianExtensions>'\
-        '<sts:InvoiceControl>'\
-        '<sts:InvoiceAuthorization>123456789</sts:InvoiceAuthorization>'\
-        '</sts:InvoiceControl></sts:DianExtensions></ext:ExtensionContent></ext:UBLExtension></ext:UBLExtensions></root>'
+    assert xml.tostring().strip() == (
+        '<root xmlns:ext="https://ext" xmlns:sts="https://sts">'
+        '<ext:UBLExtensions>'
+        '<ext:UBLExtension>'
+        '<ext:ExtensionContent>'
+        '<sts:DianExtensions>'
+        '<sts:InvoiceControl>'
+        '<sts:InvoiceAuthorization>123456789</sts:InvoiceAuthorization>'
+        '</sts:InvoiceControl></sts:DianExtensions>'
+        '</ext:ExtensionContent></ext:UBLExtension>'
+        '</ext:UBLExtensions></root>')
+
 
 def test_facho_xmlns_idempotent():
     xml = facho.FachoXML('root', nsmap={
@@ -87,16 +100,22 @@ def test_facho_xmlns_idempotent():
     })
 
     xml.find_or_create_element('/root/ext:Extension/sts:Sotoros')
-    assert xml.tostring() == '<root xmlns:ext="https://ext" xmlns:sts="https://sts"><ext:Extension><sts:Sotoros/></ext:Extension></root>'
+    assert xml.tostring() == (
+        '<root xmlns:ext="https://ext" xmlns:sts="https://sts">'
+        '<ext:Extension><sts:Sotoros/></ext:Extension></root>')
 
     xml.find_or_create_element('/root/ext:Extension/sts:Sotoros')
-    assert xml.tostring() == '<root xmlns:ext="https://ext" xmlns:sts="https://sts"><ext:Extension><sts:Sotoros/></ext:Extension></root>'
+    assert xml.tostring() == (
+        '<root xmlns:ext="https://ext" xmlns:sts="https://sts">'
+        '<ext:Extension><sts:Sotoros/></ext:Extension></root>')
+
 
 def test_facho_xml_set_element_with_format():
     xml = facho.FachoXML('root')
-    invoice = xml.set_element('/root/Invoice', 1, format_='%02d')
+    xml.set_element('/root/Invoice', 1, format_='%02d')
     assert xml.tostring() == '<root><Invoice>01</Invoice></root>'
 
+
 def test_facho_xml_fragment():
     xml = facho.FachoXML('root')
     invoice = xml.fragment('/root/Invoice')
@@ -116,7 +135,10 @@ def test_facho_xml_fragments():
     line = xml.fragment('/Invoice/Line', append=True)
     line.set_element('/Line/Id', 3)
 
-    assert xml.tostring() == '<Invoice><Line><Id>1</Id></Line><Line><Id>2</Id></Line><Line><Id>3</Id></Line></Invoice>'
+    assert xml.tostring() == (
+        '<Invoice><Line><Id>1</Id></Line><Line><Id>2</Id></Line>'
+        '<Line><Id>3</Id></Line></Invoice>')
+
 
 def test_facho_xml_nested_fragments():
     xml = facho.FachoXML('Invoice')
@@ -128,15 +150,20 @@ def test_facho_xml_nested_fragments():
 
     party.set_element('/Party/LastName', 'test')
 
-    assert xml.tostring() == '<Invoice><Party><Name>test</Name><Address><Line>line 1</Line></Address><LastName>test</LastName></Party></Invoice>'
+    assert xml.tostring() == (
+        '<Invoice><Party><Name>test</Name>'
+        '<Address><Line>line 1</Line></Address>'
+        '<LastName>test</LastName></Party></Invoice>')
+
 
 def test_facho_xml_get_element_text_of_fragment():
     xml = facho.FachoXML('root')
     invoice = xml.fragment('/root/Invoice')
     invoice.set_element('/Invoice/Id', 1)
-    
+
     assert invoice.get_element_text('/Invoice/Id') == '1'
 
+
 def test_facho_xml_get_element_text():
     xml = facho.FachoXML('Invoice')
     xml.set_element('/Invoice/ID', 'ABC123')
@@ -147,6 +174,7 @@ def test_facho_xml_get_element_text():
     line.set_element('/Line/Quantity', 5)
     assert line.get_element_text('/Line/Quantity', format_=int) == 5
 
+
 def test_facho_xml_get_element_text_next_child():
     xml = facho.FachoXML('Invoice')
     xml.set_element('/Invoice/ID', 'ABC123')
@@ -166,25 +194,32 @@ def test_facho_xml_set_element_relative():
 
     assert xml.get_element_text('/Invoice/ID') == 'ABC123'
 
+
 def test_facho_xml_set_element_relative_with_namespace():
-    xml = facho.FachoXML('{%s}Invoice' % ('http://www.dian.gov.co/contratos/facturaelectronica/v1'),
-                         nsmap={'fe': 'http://www.dian.gov.co/contratos/facturaelectronica/v1'})
+    xml = facho.FachoXML(
+        '{%s}Invoice' %
+        ('http://www.dian.gov.co/contratos/facturaelectronica/v1'),
+        nsmap={
+            'fe': 'http://www.dian.gov.co/contratos/facturaelectronica/v1'})
     xml.set_element('./ID', 'ABC123')
 
     assert xml.get_element_text('/fe:Invoice/ID') == 'ABC123'
 
+
 def test_facho_xml_fragment_relative():
     xml = facho.FachoXML('root')
     invoice = xml.fragment('./Invoice')
     invoice.set_element('./Id', 1)
     assert xml.tostring() == '<root><Invoice><Id>1</Id></Invoice></root>'
 
+
 def test_facho_xml_get_element_fragment_relative():
     xml = facho.FachoXML('root')
     invoice = xml.fragment('./Invoice')
     invoice.set_element('./Id', 1)
     assert invoice.get_element_text('./Id') == '1'
 
+
 def test_facho_xml_replacement_for():
     xml = facho.FachoXML('root')
     xml.placeholder_for('./child/type')
@@ -192,37 +227,47 @@ def test_facho_xml_replacement_for():
                         './child/code', 'test')
     assert xml.tostring() == '<root><child><code>test</code></child></root>'
 
+
 def test_facho_xml_set_element_content_invalid_validation():
     xml = facho.FachoXML('root')
 
-    with pytest.raises(facho.FachoValueInvalid) as e:
+    with pytest.raises(facho.FachoValueInvalid):
         xml.set_element_validator('./Id', lambda text, attrs: text == 'mero')
         xml.set_element('./Id', 'bad')
 
+
 def test_facho_xml_set_element_content_valid_validation():
     xml = facho.FachoXML('root')
 
     xml.set_element_validator('./Id', lambda text, attrs: text == 'mero')
     xml.set_element('./Id', 'mero')
 
+
 def test_facho_xml_set_element_attribute_invalid_validation():
     xml = facho.FachoXML('root')
 
-    with pytest.raises(facho.FachoValueInvalid) as e:
-        xml.set_element_validator('./Id', lambda text, attrs: attrs['code'] == 'ABC')
-        xml.set_element('./Id', 'mero', code = 'CBA')
+    with pytest.raises(facho.FachoValueInvalid):
+        xml.set_element_validator(
+            './Id', lambda text, attrs: attrs['code'] == 'ABC')
+        xml.set_element('./Id', 'mero', code='CBA')
+
 
 def test_facho_xml_set_element_attribute_valid_validation():
     xml = facho.FachoXML('root')
 
-    xml.set_element_validator('./Id', lambda text, attrs: attrs['code'] == 'ABC')
-    xml.set_element('./Id', 'mero', code = 'ABC')
+    xml.set_element_validator(
+        './Id',
+        lambda text,
+        attrs: attrs['code'] == 'ABC')
+    xml.set_element('./Id', 'mero', code='ABC')
+
 
 def test_facho_xml_get_element_attribute():
     xml = facho.FachoXML('root')
-    xml.set_element('./Id', 'mero', code = 'ABC')
+    xml.set_element('./Id', 'mero', code='ABC')
     assert xml.get_element_attribute('/root/Id', 'code') == 'ABC'
 
+
 def test_facho_xml_keep_orden_slibing():
     xml = facho.FachoXML('root')
     xml.find_or_create_element('./A')
@@ -233,14 +278,16 @@ def test_facho_xml_keep_orden_slibing():
 
     assert xml.tostring() == '<root><A/><A/><B/><B/><C/></root>'
 
+
 def test_facho_xml_placeholder_optional():
     xml = facho.FachoXML('root')
     xml.placeholder_for('./A')
     xml.placeholder_for('./B', optional=True)
     xml.placeholder_for('./C')
-    
+
     assert xml.tostring() == '<root><A/><C/></root>'
 
+
 def test_facho_xml_placeholder_append_to_optional():
     xml = facho.FachoXML('root')
     xml.placeholder_for('./A')
@@ -250,6 +297,7 @@ def test_facho_xml_placeholder_append_to_optional():
     xml.find_or_create_element('./B')
     assert xml.tostring() == '<root><A/><B/><C/></root>'
 
+
 def test_facho_xml_placeholder_set_element_to_optional():
     xml = facho.FachoXML('root')
     xml.placeholder_for('./A')
@@ -259,6 +307,7 @@ def test_facho_xml_placeholder_set_element_to_optional():
     xml.set_element('./B', '2')
     assert xml.tostring() == '<root><A/><B>2</B><C/></root>'
 
+
 def test_facho_xml_placeholder_set_element_to_optional_with_append():
     xml = facho.FachoXML('root')
     xml.placeholder_for('./A')
@@ -275,8 +324,8 @@ def test_facho_xml_set_attributes():
     xml.find_or_create_element('./A')
 
     xml.set_attributes('./A',
-                       value1 = '1',
-                       value2 = '2'
+                       value1='1',
+                       value2='2'
                        )
     assert xml.get_element_attribute('/root/A', 'value1') == '1'
     assert xml.get_element_attribute('/root/A', 'value2') == '2'
@@ -287,13 +336,14 @@ def test_facho_xml_set_attributes_not_set_optional():
     xml.find_or_create_element('./A')
 
     xml.set_attributes('./A',
-                       value1 = None,
-                       value2 = '2'
+                       value1=None,
+                       value2='2'
                        )
     with pytest.raises(KeyError):
         xml.get_element_attribute('/root/A', 'value1')
     assert xml.get_element_attribute('/root/A', 'value2') == '2'
 
+
 def test_facho_xml_placeholder_with_fragment():
     xml = facho.FachoXML('root')
     xml.placeholder_for('./A')
@@ -305,8 +355,10 @@ def test_facho_xml_placeholder_with_fragment():
     AA.find_or_create_element('./B', append=True)
 
     AA = xml.fragment('./AA/Child', append=True)
-    
-    assert xml.tostring() == '<root><A/><AA><Child><B/><B/></Child><Child/></AA><AAA/></root>'
+
+    assert xml.tostring() == (
+        '<root><A/><AA><Child><B/><B/></Child><Child/></AA><AAA/></root>')
+
 
 def test_facho_xml_create_on_first_append():
     xml = facho.FachoXML('root')
@@ -314,6 +366,7 @@ def test_facho_xml_create_on_first_append():
     xml.find_or_create_element('./A', append=True)
     assert xml.tostring() == '<root><A/></root>'
 
+
 def test_facho_xml_create_on_first_append_multiple_appends():
     xml = facho.FachoXML('root')
 
@@ -324,6 +377,7 @@ def test_facho_xml_create_on_first_append_multiple_appends():
     xml.find_or_create_element('./C', append=True)
     assert xml.tostring() == '<root><B/><A/><A/><A/><C/></root>'
 
+
 def test_facho_xml_fragment_create_on_first_append():
     xml = facho.FachoXML('root')
 
@@ -333,6 +387,7 @@ def test_facho_xml_fragment_create_on_first_append():
     A.find_or_create_element('./C')
     assert xml.tostring() == '<root><A><B/></A><A><C/></A></root>'
 
+
 def test_facho_xml_placeholder_optional_and_fragment():
     xml = facho.FachoXML('root')
 
@@ -346,6 +401,7 @@ def test_facho_xml_placeholder_optional_and_fragment():
 
     assert xml.tostring() == '<root><A><AA><B/><C/></AA></A></root>'
 
+
 def test_facho_xml_placeholder_optional_and_set_attributes():
     xml = facho.FachoXML('root')
     xml.placeholder_for('./A')
@@ -354,6 +410,7 @@ def test_facho_xml_placeholder_optional_and_set_attributes():
     assert xml.get_element_attribute('/root/A', 'prueba') == 'OK'
     assert xml.tostring() == '<root><A prueba="OK"/></root>'
 
+
 def test_facho_xml_placeholder_optional_and_fragment_with_set_element():
     xml = facho.FachoXML('root')
 
@@ -365,17 +422,19 @@ def test_facho_xml_placeholder_optional_and_fragment_with_set_element():
     assert xml.tostring() == '<root><A><AA prueba="OK"/></A></root>'
     assert xml.get_element_attribute('/root/A/AA', 'prueba') == 'OK'
 
+
 def test_facho_xml_exist_element():
     xml = facho.FachoXML('root')
 
     xml.placeholder_for('./A')
-    assert xml.exist_element('/root/A') == False
+    assert xml.exist_element('/root/A') is False
     assert xml.tostring() == '<root><A/></root>'
-    
+
     xml.find_or_create_element('./A')
-    assert xml.exist_element('/root/A') == True
+    assert xml.exist_element('/root/A')
     assert xml.tostring() == '<root><A/></root>'
 
+
 def test_facho_xml_query_element_text_or_attribute():
     xml = facho.FachoXML('root')
 
@@ -384,6 +443,7 @@ def test_facho_xml_query_element_text_or_attribute():
     assert xml.get_element_text_or_attribute('/root/A') == 'contenido'
     assert xml.get_element_text_or_attribute('/root/A/@clave') == 'valor'
 
+
 def test_facho_xml_query_element_text_or_attribute_from_fragment():
     xml = facho.FachoXML('root')
 
@@ -392,6 +452,7 @@ def test_facho_xml_query_element_text_or_attribute_from_fragment():
 
     assert invoice.get_element_text_or_attribute('/Invoice/A') == 'contenido'
 
+
 def test_facho_xml_build_xml_absolute():
     xml = facho.FachoXML('root')
 
@@ -400,18 +461,23 @@ def test_facho_xml_build_xml_absolute():
 
 
 def test_facho_xml_build_xml_absolute_namespace():
-    xml = facho.FachoXML('{%s}root' % ('http://www.dian.gov.co/contratos/facturaelectronica/v1'),
-                         nsmap={'fe': 'http://www.dian.gov.co/contratos/facturaelectronica/v1'})
+    xml = facho.FachoXML(
+        '{%s}root' %
+        ('http://www.dian.gov.co/contratos/facturaelectronica/v1'),
+        nsmap={
+            'fe': 'http://www.dian.gov.co/contratos/facturaelectronica/v1'})
 
     xpath = xml.xpath_from_root('/A')
     assert xpath == '/fe:root/A'
 
 
 def test_facho_xml_build_xml_absolute_namespace_from_fragment():
-    xml = facho.FachoXML('{%s}root' % ('http://www.dian.gov.co/contratos/facturaelectronica/v1'),
-                         nsmap={'fe': 'http://www.dian.gov.co/contratos/facturaelectronica/v1'})
+    xml = facho.FachoXML(
+        '{%s}root' %
+        ('http://www.dian.gov.co/contratos/facturaelectronica/v1'),
+        nsmap={
+            'fe': 'http://www.dian.gov.co/contratos/facturaelectronica/v1'})
     invoice = xml.fragment('/root/Invoice')
-    
+
     xpath = invoice.xpath_from_root('/A')
     assert xpath == '/fe:root/Invoice/A'
-
diff --git a/tests/test_fe.py b/tests/test_fe.py
index 29aca4b..6c84e91 100644
--- a/tests/test_fe.py
+++ b/tests/test_fe.py
@@ -4,16 +4,14 @@
 # this repository contains the full copyright notices and license terms.
 from datetime import datetime
 
-import pytest
-
 from facho import fe
 
-import helpers
-
 
 def test_xmlsigned_build(monkeypatch):
-    # openssl req -x509 -sha256 -nodes -subj "/CN=test" -days 1 -newkey rsa:2048 -keyout example.key -out example.pem
-    # openssl pkcs12 -export -out example.p12 -inkey example.key -in example.pem
+    # openssl req -x509 -sha256 -nodes -subj "/CN=test" -days 1
+    # -newkey rsa:2048 -keyout example.key -out example.pem
+    # openssl pkcs12 -export -out example.p12 -inkey example.key -in
+    # example.pem
     signer = fe.DianXMLExtensionSigner('./tests/example.p12')
 
     xml = fe.FeXML('Invoice',
@@ -21,68 +19,90 @@ def test_xmlsigned_build(monkeypatch):
 
     signer.sign_xml_element(xml.root)
 
-    elem = xml.find_or_create_element('/fe:Invoice/ext:UBLExtensions/ext:UBLExtension/ext:ExtensionContent/ds:Signature')
+    elem = xml.find_or_create_element(
+        '/fe:Invoice/ext:UBLExtensions/ext:UBLExtension/ext:ExtensionContent'
+        '/ds:Signature')
 
     assert elem is not None
-    #assert elem.findall('ds:SignedInfo', fe.NAMESPACES) is not None
+    # assert elem.findall('ds:SignedInfo', fe.NAMESPACES) is not None
 
 
 def test_xmlsigned_with_passphrase_build(monkeypatch):
-    #openssl req -x509 -sha256 -nodes -subj "/CN=test" -days 1 -newkey rsa:2048 -keyout example.key -out example.pem
-    #openssl pkcs12 -export -out example.p12 -inkey example.key -in example.pem
-    signer = fe.DianXMLExtensionSigner('./tests/example-with-passphrase.p12', 'test')
+    # openssl req -x509 -sha256 -nodes -subj "/CN=test" -days 1
+    # -newkey rsa:2048 -keyout example.key -out example.pem
+    # openssl pkcs12 -export -out example.p12 -inkey example.key -in
+    # example.pem
+    signer = fe.DianXMLExtensionSigner(
+        './tests/example-with-passphrase.p12', 'test')
 
     xml = fe.FeXML('Invoice',
                    'http://www.dian.gov.co/contratos/facturaelectronica/v1')
 
     signer.sign_xml_element(xml.root)
 
-    elem = xml.find_or_create_element('/fe:Invoice/ext:UBLExtensions/ext:UBLExtension/ext:ExtensionContent/ds:Signature')
+    elem = xml.find_or_create_element(
+        '/fe:Invoice/ext:UBLExtensions/ext:UBLExtension/ext:ExtensionContent'
+        '/ds:Signature')
 
     assert elem is not None
-    #assert elem.findall('ds:SignedInfo', fe.NAMESPACES) is not None
+    # assert elem.findall('ds:SignedInfo', fe.NAMESPACES) is not None
 
 
 def test_dian_extension_software_security_code():
-    security_code = fe.DianXMLExtensionSoftwareSecurityCode('idsoftware', '1234', '1')
+    security_code = fe.DianXMLExtensionSoftwareSecurityCode(
+        'idsoftware', '1234', '1')
     xml = fe.FeXML('Invoice',
                    'http://www.dian.gov.co/contratos/facturaelectronica/v1')
     xml.add_extension(security_code)
-    content = xml.get_element_text('/fe:Invoice/ext:UBLExtensions/ext:UBLExtension/ext:ExtensionContent/sts:DianExtensions/sts:SoftwareSecurityCode')
+    content = xml.get_element_text(
+        '/fe:Invoice/ext:UBLExtensions/ext:UBLExtension/ext:ExtensionContent'
+        '/sts:DianExtensions/sts:SoftwareSecurityCode')
     assert content is not None
 
+
 def test_dian_extension_invoice_authorization():
     invoice_authorization = '18762002346472'
-    inv_auth_ext = fe.DianXMLExtensionInvoiceAuthorization(invoice_authorization,
-                                                           datetime(2017, 2, 23),
-                                                           datetime(2019, 8, 23),
-                                                           'MD', 100001, 174999)
+    inv_auth_ext = fe.DianXMLExtensionInvoiceAuthorization(
+        invoice_authorization, datetime(
+            2017, 2, 23), datetime(
+            2019, 8, 23), 'MD', 100001, 174999)
     xml = fe.FeXML('Invoice',
                    'http://www.dian.gov.co/contratos/facturaelectronica/v1')
     xml.add_extension(inv_auth_ext)
-    auth = xml.get_element_text('/fe:Invoice/ext:UBLExtensions/ext:UBLExtension/ext:ExtensionContent/sts:DianExtensions/sts:InvoiceControl/sts:InvoiceAuthorization')
+    auth = xml.get_element_text(
+        '/fe:Invoice/ext:UBLExtensions/ext:UBLExtension/ext:ExtensionContent'
+        '/sts:DianExtensions/sts:InvoiceControl/sts:InvoiceAuthorization')
     assert auth == invoice_authorization
 
+
 def test_dian_extension_software_provider():
     nit = '123456789'
     id_software = 'ABCDASDF123'
-    software_provider_extension = fe.DianXMLExtensionSoftwareProvider(nit, '', id_software)
+    software_provider_extension = fe.DianXMLExtensionSoftwareProvider(
+        nit, '', id_software)
 
     xml = fe.FeXML('Invoice',
                    'http://www.dian.gov.co/contratos/facturaelectronica/v1')
     xml.add_extension(software_provider_extension)
 
-    give_nit = xml.get_element_text('/fe:Invoice/ext:UBLExtensions/ext:UBLExtension/ext:ExtensionContent/sts:DianExtensions/sts:SoftwareProvider/sts:ProviderID')
+    give_nit = xml.get_element_text(
+        '/fe:Invoice/ext:UBLExtensions/ext:UBLExtension/ext:ExtensionContent'
+        '/sts:DianExtensions/sts:SoftwareProvider/sts:ProviderID')
     assert nit == give_nit
 
+
 def test_dian_extension_authorization_provider():
     auth_provider_extension = fe.DianXMLExtensionAuthorizationProvider()
     xml = fe.FeXML('Invoice',
                    'http://www.dian.gov.co/contratos/facturaelectronica/v1')
     xml.add_extension(auth_provider_extension)
-    dian_nit = xml.get_element_text('/fe:Invoice/ext:UBLExtensions/ext:UBLExtension/ext:ExtensionContent/sts:DianExtensions/sts:AuthorizationProvider/sts:AuthorizationProviderID')
+    dian_nit = xml.get_element_text(
+        '/fe:Invoice/ext:UBLExtensions/ext:UBLExtension/'
+        'ext:ExtensionContent/sts:DianExtensions/sts:AuthorizationProvider/'
+        'sts:AuthorizationProviderID')
     assert dian_nit == '800197268'
 
+
 def test_dian_invoice_without_namespace_in_root():
     xml = fe.FeXML('Invoice',
                    'http://www.dian.gov.co/contratos/facturaelectronica/v1')
@@ -92,10 +112,14 @@ def test_dian_invoice_without_namespace_in_root():
 
 def test_xml_sign_dian(monkeypatch):
     xml = fe.FeXML('Invoice',
-                'http://www.dian.gov.co/contratos/facturaelectronica/v1')
-    xml.find_or_create_element('/fe:Invoice/ext:UBLExtensions/ext:UBLExtension/ext:ExtensionContent')
-    ublextension = xml.fragment('/fe:Invoice/ext:UBLExtensions/ext:UBLExtension', append=True)
-    extcontent = ublextension.find_or_create_element('/ext:UBLExtension/ext:ExtensionContent')
+                   'http://www.dian.gov.co/contratos/facturaelectronica/v1')
+    xml.find_or_create_element(
+        '/fe:Invoice/ext:UBLExtensions/ext:UBLExtension/ext:ExtensionContent')
+    ublextension = xml.fragment(
+        '/fe:Invoice/ext:UBLExtensions/ext:UBLExtension',
+        append=True)
+    ublextension.find_or_create_element(
+        '/ext:UBLExtension/ext:ExtensionContent')
 
     xmlstring = xml.tostring()
     print(xmlstring)
@@ -103,12 +127,17 @@ def test_xml_sign_dian(monkeypatch):
     xmlsigned = signer.sign_xml_string(xmlstring)
     assert "Signature" in xmlsigned
 
+
 def test_xml_sign_dian_using_bytes(monkeypatch):
     xml = fe.FeXML('Invoice',
-                'http://www.dian.gov.co/contratos/facturaelectronica/v1')
-    xml.find_or_create_element('/fe:Invoice/ext:UBLExtensions/ext:UBLExtension/ext:ExtensionContent')
-    ublextension = xml.fragment('/fe:Invoice/ext:UBLExtensions/ext:UBLExtension', append=True)
-    extcontent = ublextension.find_or_create_element('/ext:UBLExtension/ext:ExtensionContent')
+                   'http://www.dian.gov.co/contratos/facturaelectronica/v1')
+    xml.find_or_create_element(
+        '/fe:Invoice/ext:UBLExtensions/ext:UBLExtension/ext:ExtensionContent')
+    ublextension = xml.fragment(
+        '/fe:Invoice/ext:UBLExtensions/ext:UBLExtension',
+        append=True)
+    ublextension.find_or_create_element(
+        '/ext:UBLExtension/ext:ExtensionContent')
 
     xmlstring = xml.tostring()
     p12_data = open('./tests/example.p12', 'rb').read()
@@ -117,6 +146,7 @@ def test_xml_sign_dian_using_bytes(monkeypatch):
     xmlsigned = signer.sign_xml_string(xmlstring)
     assert "Signature" in xmlsigned
 
+
 def test_xml_signature_timestamp(monkeypatch):
     xml = fe.FeXML(
         'Invoice',
@@ -132,4 +162,4 @@ def test_xml_signature_timestamp(monkeypatch):
     xmlsigned = signer.sign_xml_string(xmlstring)
 
     with open('invoice.xml', 'w') as file_:
-        file_.write(xmlsigned)
\ No newline at end of file
+        file_.write(xmlsigned)
diff --git a/tests/test_fe_form.py b/tests/test_fe_form.py
index cfbc060..b4c226c 100644
--- a/tests/test_fe_form.py
+++ b/tests/test_fe_form.py
@@ -41,11 +41,13 @@ def test_invoicesimple_build(simple_invoice):
     xml = DIANInvoiceXML(simple_invoice)
 
     supplier_name = xml.get_element_text(
-        '/fe:Invoice/cac:AccountingSupplierParty/cac:Party/cac:PartyName/cbc:Name')
+        '/fe:Invoice/cac:AccountingSupplierParty/cac:Party/cac:PartyName/cbc'
+        ':Name')
     assert supplier_name == simple_invoice.invoice_supplier.name
 
     customer_name = xml.get_element_text(
-        '/fe:Invoice/cac:AccountingCustomerParty/cac:Party/cac:PartyName/cbc:Name')
+        '/fe:Invoice/cac:AccountingCustomerParty/cac:Party/cac:PartyName/cbc'
+        ':Name')
     assert customer_name == simple_invoice.invoice_customer.name
 
 
@@ -66,7 +68,8 @@ def test_invoicesimple_xml_signed(monkeypatch, simple_invoice):
     xml.add_extension(signer)
 
     elem = xml.get_element(
-        '/fe:Invoice/ext:UBLExtensions/ext:UBLExtension[2]/ext:ExtensionContent/ds:Signature')
+        '/fe:Invoice/ext:UBLExtensions/ext:UBLExtension[2]/ext'
+        ':ExtensionContent/ds:Signature')
     assert elem.text is not None
 
 
@@ -75,14 +78,16 @@ def test_invoicesimple_zip(simple_invoice):
 
     zipdata = io.BytesIO()
     with fe.DianZIP(zipdata) as dianzip:
-        name_invoice = dianzip.add_invoice_xml(simple_invoice.invoice_ident, str(xml_invoice))
+        name_invoice = dianzip.add_invoice_xml(
+            simple_invoice.invoice_ident, str(xml_invoice))
 
     # el zip ademas de archivar debe comprimir los archivos
     # de lo contrario la DIAN lo rechaza
     with zipfile.ZipFile(zipdata) as dianzip:
         dianzip.testzip()
         for zipinfo in dianzip.infolist():
-            assert zipinfo.compress_type == zipfile.ZIP_DEFLATED, "se espera el zip comprimido"
+            assert zipinfo.compress_type == zipfile.ZIP_DEFLATED, (
+                "se espera el zip comprimido")
 
     with zipfile.ZipFile(zipdata) as dianzip:
         xml_data = dianzip.open(name_invoice).read().decode('utf-8')
@@ -122,7 +127,8 @@ def test_invoice_invoice_type_code(simple_invoice):
 def test_invoice_totals(simple_invoice_without_lines):
     simple_invoice = simple_invoice_without_lines
     simple_invoice.invoice_ident = '323200000129'
-    simple_invoice.invoice_issue = datetime.strptime('2019-01-16 10:53:10-05:00', '%Y-%m-%d %H:%M:%S%z')
+    simple_invoice.invoice_issue = datetime.strptime(
+        '2019-01-16 10:53:10-05:00', '%Y-%m-%d %H:%M:%S%z')
     simple_invoice.invoice_supplier.ident = '700085371'
     simple_invoice.invoice_customer.ident = '800199436'
     simple_invoice.add_invoice_line(form.InvoiceLine(
@@ -222,7 +228,8 @@ def test_invoice_cufe(simple_invoice_without_lines):
     assert formatVars[12] == '800199436', "NumAdq"
 
     # ClTec
-    assert formatVars[13] == '693ff6f2a553c3646a063436fd4dd9ded0311471', "ClTec"
+    assert formatVars[13] == (
+        '693ff6f2a553c3646a063436fd4dd9ded0311471'), "ClTec"
 
     # TipoAmbiente
     assert formatVars[14] == '1', "TipoAmbiente"
@@ -323,8 +330,13 @@ def test_debit_note_cude(simple_debit_note_without_lines):
     assert build_vars['TipoAmb'] == 2
 
     cude_composicion = "".join(cude_extension.formatVars())
-    assert cude_composicion == 'ND10012019-01-1810:58:00-05:0030000.00010.00042400.00030.0032400.0090019726410254102102012'
+    assert cude_composicion == (
+        'ND10012019-01-1810:58:00-05:0030000.00010.00042400.00030.0032400.009'
+        '001'
+        '9726410254102102012')
 
     xml_invoice.add_extension(cude_extension)
     cude = xml_invoice.get_element_text('/fe:DebitNote/cbc:UUID')
-    assert cude == '3fa73a86d57d9341c536afde1f85c4efd9d4591c2c22bce4dfb0e6b0d2e83b8f047a8bde7098292e9d2493e60d1c31da'
+    assert cude == (
+        '3fa73a86d57d9341c536afde1f85c4efd9d4591c2c22bce4dfb0e6b0d2e83b8f047a8'
+        'bde7098292e9d2493e60d1c31da')
diff --git a/tests/test_form.py b/tests/test_form.py
index 2e2559a..713a0eb 100644
--- a/tests/test_form.py
+++ b/tests/test_form.py
@@ -121,7 +121,9 @@ def test_FAU14():
 
     wants = form.Amount(119.0 + 19.0 - 50.0)
 
-    assert inv.invoice_legal_monetary_total.payable_amount == wants, "got %s want %s" % (inv.invoice_legal_monetary_total.payable_amount, wants)
+    assert inv.invoice_legal_monetary_total.payable_amount == wants, (
+        "got %s want %s" % (
+            inv.invoice_legal_monetary_total.payable_amount, wants))
 
 
 def test_invalid_tipo_operacion_nota_debito():
diff --git a/tests/test_form_xml.py b/tests/test_form_xml.py
index 44a4ccc..aa83439 100644
--- a/tests/test_form_xml.py
+++ b/tests/test_form_xml.py
@@ -6,10 +6,7 @@
 """Tests for `facho` package."""
 
 import pytest
-# from datetime import datetime
-import copy
 
-from facho.fe import form
 from facho.fe import form_xml
 # from fixtures import *
 
diff --git a/tests/test_nomina.py b/tests/test_nomina.py
index 961bb77..a130b9a 100644
--- a/tests/test_nomina.py
+++ b/tests/test_nomina.py
@@ -28,8 +28,12 @@
 #     ))
 
 #     xml = nomina.toFachoXML()
-#     assert xml.get_element_attribute('/nomina:NominaIndividual/Devengados/Basico', 'DiasTrabajados') == '30'
-#     assert xml.get_element_attribute('/nomina:NominaIndividual/Devengados/Basico', 'SueldoTrabajado') == '1000000.00'
+#      assert
+# xml.get_element_attribute('/nomina:NominaIndividual/Devengados/Basico',
+# 'DiasTrabajados') == '30'
+#      assert
+# xml.get_element_attribute('/nomina:NominaIndividual/Devengados/Basico',
+# 'SueldoTrabajado') == '1000000.00'
 
 # def test_adicionar_devengado_transporte():
 #     nomina = fe.nomina.DIANNominaIndividual()
@@ -40,7 +44,9 @@
 
 #     xml = nomina.toFachoXML()
 
-#     assert xml.get_element_attribute('/nomina:NominaIndividual/Devengados/Transporte', 'AuxilioTransporte') == '2000000.0'
+#      assert
+# xml.get_element_attribute('/nomina:NominaIndividual/Devengados/Transporte',
+# 'AuxilioTransporte') == '2000000.0'
 
 # def test_adicionar_devengado_comprobante_total():
 #     nomina = fe.nomina.DIANNominaIndividual()
@@ -58,7 +64,9 @@
 
 #     xml = nomina.toFachoXML()
 
-#     assert xml.get_element_text('/nomina:NominaIndividual/ComprobanteTotal') == '1000000.00'
+#      assert
+# xml.get_element_text('/nomina:NominaIndividual/ComprobanteTotal') ==
+# '1000000.00'
 
 # def test_adicionar_devengado_comprobante_total_cero():
 #     nomina = fe.nomina.DIANNominaIndividual()
@@ -75,7 +83,8 @@
 
 #     xml = nomina.toFachoXML()
 
-#     assert xml.get_element_text('/nomina:NominaIndividual/ComprobanteTotal') == '0.00'
+#      assert
+# xml.get_element_text('/nomina:NominaIndividual/ComprobanteTotal') == '0.00'
 
 # def test_adicionar_devengado_transporte_muchos():
 #     nomina = fe.nomina.DIANNominaIndividual()
@@ -90,7 +99,8 @@
 
 #     xml = nomina.toFachoXML()
 #     print(xml)
-#     assert xml.get_element_text('/nomina:NominaIndividual/DevengadosTotal') == '5000000.00'
+#      assert xml.get_element_text('/nomina:NominaIndividual/DevengadosTotal')
+# == '5000000.00'
 
 # def test_adicionar_deduccion_salud():
 #     nomina = fe.nomina.DIANNominaIndividual()
@@ -107,7 +117,9 @@
 
 #     xml = nomina.toFachoXML()
 #     print(xml)
-#     assert xml.get_element_text('/nomina:NominaIndividual/DeduccionesTotal') == '1000.00'
+#      assert
+# xml.get_element_text('/nomina:NominaIndividual/DeduccionesTotal') ==
+# '1000.00'
 
 # def test_nomina_obligatorios_segun_anexo_tecnico():
 #     nomina = fe.nomina.DIANNominaIndividual()
@@ -213,26 +225,62 @@
 #     ))
 
 #     xml = nomina.toFachoXML()
-#     expected_cune = 'b8f9b6c24de07ffd92ea5467433a3b69357cfaffa7c19722db94b2e0eca41d057085a54f484b5da15ff585e773b0b0ab'
-#     assert xml.get_element_attribute('/nomina:NominaIndividual/InformacionGeneral', 'CUNE') == expected_cune
-#     assert xml.get_element_attribute('/nomina:NominaIndividual/InformacionGeneral', 'TipoXML') == '102'
-#     assert xml.get_element_text_or_attribute('/nomina:NominaIndividual/NumeroSecuenciaXML/@Numero') == 'N00001'
-#     assert xml.get_element_text_or_attribute('/nomina:NominaIndividual/NumeroSecuenciaXML/@Consecutivo') == '00001'
-#     assert xml.get_element_text_or_attribute('/nomina:NominaIndividual/LugarGeneracionXML/@Pais') == 'CO'
-#     assert xml.get_element_text_or_attribute('/nomina:NominaIndividual/LugarGeneracionXML/@DepartamentoEstado') == '05'
-#     assert xml.get_element_text_or_attribute('/nomina:NominaIndividual/LugarGeneracionXML/@MunicipioCiudad') == '05001'
-#     assert xml.get_element_text_or_attribute('/nomina:NominaIndividual/ProveedorXML/@NIT') == '999999'
-#     assert xml.get_element_text_or_attribute('/nomina:NominaIndividual/ProveedorXML/@DV') == '2'
-#     assert xml.get_element_text_or_attribute('/nomina:NominaIndividual/ProveedorXML/@SoftwareID') == 'xx'
-#     assert xml.get_element_text_or_attribute('/nomina:NominaIndividual/ProveedorXML/@SoftwareSC') is not None
-#     assert xml.get_element_text_or_attribute('/nomina:NominaIndividual/CodigoQR') == f"https://catalogo-vpfe.dian.gov.co/document/searchqr?documentkey={expected_cune}"
-#     assert xml.get_element_text_or_attribute('/nomina:NominaIndividual/Empleador/@NIT') == '700085371'
-#     assert xml.get_element_text_or_attribute('/nomina:NominaIndividual/Trabajador/@NumeroDocumento') == '800199436'
-#     assert xml.get_element_text_or_attribute('/nomina:NominaIndividual/Novedad') == 'True'
-#     assert xml.get_element_text_or_attribute('/nomina:NominaIndividual/Novedad/@CUNENov') == 'N0111'
+#      expected_cune =
+# 'b8f9b6c24de07ffd92ea5467433a3b69357cfaffa7c19722db94b2e0eca41d057085a54f484
+# b5da15ff585e773b0b0ab'
+#      assert
+# xml.get_element_attribute('/nomina:NominaIndividual/InformacionGeneral',
+# 'CUNE') == expected_cune
+#      assert
+# xml.get_element_attribute('/nomina:NominaIndividual/InformacionGeneral',
+# 'TipoXML') == '102'
+#      assert
+# xml.get_element_text_or_attribute('/nomina:NominaIndividual/NumeroSecuenciaX
+# ML/@Numero') == 'N00001'
+#      assert
+# xml.get_element_text_or_attribute('/nomina:NominaIndividual/NumeroSecuenciaX
+# ML/@Consecutivo') == '00001'
+#      assert
+# xml.get_element_text_or_attribute('/nomina:NominaIndividual/LugarGeneracionX
+# ML/@Pais') == 'CO'
+#      assert
+# xml.get_element_text_or_attribute('/nomina:NominaIndividual/LugarGeneracionX
+# ML/@DepartamentoEstado') == '05'
+#      assert
+# xml.get_element_text_or_attribute('/nomina:NominaIndividual/LugarGeneracionX
+# ML/@MunicipioCiudad') == '05001'
+#      assert
+# xml.get_element_text_or_attribute('/nomina:NominaIndividual/ProveedorXML/@NI
+# T') == '999999'
+#      assert
+# xml.get_element_text_or_attribute('/nomina:NominaIndividual/ProveedorXML/@DV
+# ') == '2'
+#      assert
+# xml.get_element_text_or_attribute('/nomina:NominaIndividual/ProveedorXML/@So
+# ftwareID') == 'xx'
+#      assert
+# xml.get_element_text_or_attribute('/nomina:NominaIndividual/ProveedorXML/@So
+# ftwareSC') is not None
+#      assert
+# xml.get_element_text_or_attribute('/nomina:NominaIndividual/CodigoQR') ==
+# f"https://catalogo-vpfe.dian.gov.co/document/searchqr?documentkey={expected_
+# cune}"
+#      assert
+# xml.get_element_text_or_attribute('/nomina:NominaIndividual/Empleador/@NIT')
+# == '700085371'
+#      assert
+# xml.get_element_text_or_attribute('/nomina:NominaIndividual/Trabajador/@Nume
+# roDocumento') == '800199436'
+#      assert
+# xml.get_element_text_or_attribute('/nomina:NominaIndividual/Novedad') ==
+# 'True'
+#      assert
+# xml.get_element_text_or_attribute('/nomina:NominaIndividual/Novedad/@CUNENov
+# ') == 'N0111'
 
 #     # confirmar el namespace
-#     assert 'xmlns="dian:gov:co:facturaelectronica:NominaIndividual"' in xml.tostring()
+#      assert 'xmlns="dian:gov:co:facturaelectronica:NominaIndividual"' in
+# xml.tostring()
 
 # def test_asignar_pago():
 #     nomina = fe.nomina.DIANNominaIndividual()
@@ -249,11 +297,11 @@
 #     xml.add_extension(signer)
 
 #     print(xml.tostring())
-#     elem = xml.get_element('/nomina:NominaIndividual/ext:UBLExtensions/ext:UBLExtension/ext:ExtensionContent/ds:Signature')
+#      elem =
+# xml.get_element('/nomina:NominaIndividual/ext:UBLExtensions/ext:UBLExtension
+# /ext:ExtensionContent/ds:Signature')
 #     assert elem is not None
 
-
-
 # def test_nomina_devengado_horas_extras_nocturnas():
 #     nomina = fe.nomina.DIANNominaIndividual()
 
@@ -277,7 +325,9 @@
 #     ))
 
 #     xml = nomina.toFachoXML()
-#     extras = xml.get_element('/nomina:NominaIndividual/Devengados/HENs/HEN', multiple=True)
+#      extras =
+# xml.get_element('/nomina:NominaIndividual/Devengados/HENs/HEN',
+# multiple=True)
 #     assert extras[0].get('HoraInicio') == '2021-11-30T19:09:55'
 #     assert extras[0].get('HoraFin') == '2021-11-30T20:09:55'
 #     assert extras[0].get('Cantidad') == '1'
@@ -312,7 +362,9 @@
 #     ))
 
 #     xml = nomina.toFachoXML()
-#     extras = xml.get_element('/nomina:NominaIndividual/Devengados/HRNs/HRN', multiple=True)
+#      extras =
+# xml.get_element('/nomina:NominaIndividual/Devengados/HRNs/HRN',
+# multiple=True)
 #     assert extras[0].get('HoraInicio') == '2021-11-30T19:09:55'
 #     assert extras[0].get('HoraFin') == '2021-11-30T20:09:55'
 #     assert extras[0].get('Cantidad') == '1'
@@ -327,7 +379,9 @@
 # def test_nomina_devengado_horas_extras_diarias_dominicales_y_festivos():
 #     nomina = fe.nomina.DIANNominaIndividual()
 
-#     nomina.adicionar_devengado(fe.nomina.DevengadoHorasExtrasDiariasDominicalesYFestivos(
+#
+# nomina.adicionar_devengado(fe.nomina.DevengadoHorasExtrasDiariasDominicalesY
+# Festivos(
 #         horas_extras=[
 #             fe.nomina.DevengadoHoraExtra(
 #                 hora_inicio='2021-11-30T19:09:55',
@@ -347,7 +401,9 @@
 #     ))
 
 #     xml = nomina.toFachoXML()
-#     extras = xml.get_element('/nomina:NominaIndividual/Devengados/HEDDFs/HEDDF', multiple=True)
+#      extras =
+# xml.get_element('/nomina:NominaIndividual/Devengados/HEDDFs/HEDDF',
+# multiple=True)
 #     assert extras[0].get('HoraInicio') == '2021-11-30T19:09:55'
 #     assert extras[0].get('HoraFin') == '2021-11-30T20:09:55'
 #     assert extras[0].get('Cantidad') == '1'
@@ -362,7 +418,9 @@
 # def test_nomina_devengado_horas_recargo_diarias_dominicales_y_festivos():
 #     nomina = fe.nomina.DIANNominaIndividual()
 
-#     nomina.adicionar_devengado(fe.nomina.DevengadoHorasRecargoDiariasDominicalesYFestivos(
+#
+# nomina.adicionar_devengado(fe.nomina.DevengadoHorasRecargoDiariasDominicales
+# YFestivos(
 #         horas_extras=[
 #             fe.nomina.DevengadoHoraExtra(
 #                 hora_inicio='2021-11-30T19:09:55',
@@ -382,7 +440,9 @@
 #     ))
 
 #     xml = nomina.toFachoXML()
-#     extras = xml.get_element('/nomina:NominaIndividual/Devengados/HRDDFs/HRDDF', multiple=True)
+#      extras =
+# xml.get_element('/nomina:NominaIndividual/Devengados/HRDDFs/HRDDF',
+# multiple=True)
 #     assert extras[0].get('HoraInicio') == '2021-11-30T19:09:55'
 #     assert extras[0].get('HoraFin') == '2021-11-30T20:09:55'
 #     assert extras[0].get('Cantidad') == '1'
@@ -398,7 +458,9 @@
 # def test_nomina_devengado_horas_extras_nocturnas_dominicales_y_festivos():
 #     nomina = fe.nomina.DIANNominaIndividual()
 
-#     nomina.adicionar_devengado(fe.nomina.DevengadoHorasExtrasNocturnasDominicalesYFestivos(
+#
+# nomina.adicionar_devengado(fe.nomina.DevengadoHorasExtrasNocturnasDominicale
+# sYFestivos(
 #         horas_extras=[
 #             fe.nomina.DevengadoHoraExtra(
 #                 hora_inicio='2021-11-30T19:09:55',
@@ -418,7 +480,9 @@
 #     ))
 
 #     xml = nomina.toFachoXML()
-#     extras = xml.get_element('/nomina:NominaIndividual/Devengados/HENDFs/HENDF', multiple=True)
+#      extras =
+# xml.get_element('/nomina:NominaIndividual/Devengados/HENDFs/HENDF',
+# multiple=True)
 #     assert extras[0].get('HoraInicio') == '2021-11-30T19:09:55'
 #     assert extras[0].get('HoraFin') == '2021-11-30T20:09:55'
 #     assert extras[0].get('Cantidad') == '1'
@@ -433,7 +497,9 @@
 # def test_nomina_devengado_horas_recargo_nocturno_dominicales_y_festivos():
 #     nomina = fe.nomina.DIANNominaIndividual()
 
-#     nomina.adicionar_devengado(fe.nomina.DevengadoHorasRecargoNocturnoDominicalesYFestivos(
+#
+# nomina.adicionar_devengado(fe.nomina.DevengadoHorasRecargoNocturnoDominicale
+# sYFestivos(
 #         horas_extras=[
 #             fe.nomina.DevengadoHoraExtra(
 #                 hora_inicio='2021-11-30T19:09:55',
@@ -453,7 +519,9 @@
 #     ))
 
 #     xml = nomina.toFachoXML()
-#     extras = xml.get_element('/nomina:NominaIndividual/Devengados/HRNDFs/HRNDF', multiple=True)
+#      extras =
+# xml.get_element('/nomina:NominaIndividual/Devengados/HRNDFs/HRNDF',
+# multiple=True)
 #     assert extras[0].get('HoraInicio') == '2021-11-30T19:09:55'
 #     assert extras[0].get('HoraFin') == '2021-11-30T20:09:55'
 #     assert extras[0].get('Cantidad') == '1'
diff --git a/tests/test_nomina_ajuste.py b/tests/test_nomina_ajuste.py
index a20c159..a263260 100644
--- a/tests/test_nomina_ajuste.py
+++ b/tests/test_nomina_ajuste.py
@@ -101,7 +101,9 @@
 
 #     xml = nomina.toFachoXML()
 
-#     assert xml.get_element_attribute('/nominaajuste:NominaIndividualDeAjuste/Reemplazar/InformacionGeneral', 'TipoXML') == '103'
+#      assert
+# xml.get_element_attribute('/nominaajuste:NominaIndividualDeAjuste/Reemplazar
+# /InformacionGeneral', 'TipoXML') == '103'
 
 
 # def test_adicionar_reemplazar_devengado_comprobante_total():
@@ -119,13 +121,17 @@
 
 #     xml = nomina.toFachoXML()
 
-#     assert xml.get_element_text('/nominaajuste:NominaIndividualDeAjuste/Reemplazar/ComprobanteTotal') == '1000000.00'
+#      assert
+# xml.get_element_text('/nominaajuste:NominaIndividualDeAjuste/Reemplazar/Comp
+# robanteTotal') == '1000000.00'
 
 
 # def test_adicionar_reemplazar_asignar_predecesor():
 #     nomina = fe.nomina.DIANNominaIndividualDeAjuste.Reemplazar()
 
-#     nomina.asignar_predecesor(fe.nomina.DIANNominaIndividualDeAjuste.Reemplazar.Predecesor(
+#
+# nomina.asignar_predecesor(fe.nomina.DIANNominaIndividualDeAjuste.Reemplazar.
+# Predecesor(
 #         numero = '123456',
 #         cune = 'ABC123456',
 #         fecha_generacion = '2021-11-16'
@@ -133,15 +139,23 @@
 
 #     xml = nomina.toFachoXML()
 #     print(xml.tostring())
-#     assert xml.get_element_text_or_attribute('/nominaajuste:NominaIndividualDeAjuste/Reemplazar/ReemplazandoPredecesor/@NumeroPred') == '123456'
-#     assert xml.get_element_text_or_attribute('/nominaajuste:NominaIndividualDeAjuste/Reemplazar/ReemplazandoPredecesor/@CUNEPred') == 'ABC123456'
-#     assert xml.get_element_text_or_attribute('/nominaajuste:NominaIndividualDeAjuste/Reemplazar/ReemplazandoPredecesor/@FechaGenPred') == '2021-11-16'
+#      assert
+# xml.get_element_text_or_attribute('/nominaajuste:NominaIndividualDeAjuste/Re
+# emplazar/ReemplazandoPredecesor/@NumeroPred') == '123456'
+#      assert
+# xml.get_element_text_or_attribute('/nominaajuste:NominaIndividualDeAjuste/Re
+# emplazar/ReemplazandoPredecesor/@CUNEPred') == 'ABC123456'
+#      assert
+# xml.get_element_text_or_attribute('/nominaajuste:NominaIndividualDeAjuste/Re
+# emplazar/ReemplazandoPredecesor/@FechaGenPred') == '2021-11-16'
 
 
 # def test_adicionar_reemplazar_eliminar_predecesor_opcional():
 #     nomina = fe.nomina.DIANNominaIndividualDeAjuste.Reemplazar()
 
-#     nomina.asignar_predecesor(fe.nomina.DIANNominaIndividualDeAjuste.Reemplazar.Predecesor(
+#
+# nomina.asignar_predecesor(fe.nomina.DIANNominaIndividualDeAjuste.Reemplazar.
+# Predecesor(
 #         numero = '123456',
 #         cune = 'ABC123456',
 #         fecha_generacion = '2021-11-16'
@@ -150,13 +164,19 @@
 #     xml = nomina.toFachoXML()
 #     print(xml.tostring())
 
-#     assert xml.get_element('/nominaajuste:NominaIndividualDeAjuste/Reemplazar/ReemplazandoPredecesor') is not None
-#     assert xml.get_element('/nominaajuste:NominaIndividualDeAjuste/Eliminar/EliminandoPredecesor') is None
+#      assert
+# xml.get_element('/nominaajuste:NominaIndividualDeAjuste/Reemplazar/Reemplaza
+# ndoPredecesor') is not None
+#      assert
+# xml.get_element('/nominaajuste:NominaIndividualDeAjuste/Eliminar/EliminandoP
+# redecesor') is None
 
 # def test_adicionar_eliminar_reemplazar_predecesor_opcional():
 #     nomina = fe.nomina.DIANNominaIndividualDeAjuste.Eliminar()
 
-#     nomina.asignar_predecesor(fe.nomina.DIANNominaIndividualDeAjuste.Eliminar.Predecesor(
+#
+# nomina.asignar_predecesor(fe.nomina.DIANNominaIndividualDeAjuste.Eliminar.Pr
+# edecesor(
 #         numero = '123456',
 #         cune = 'ABC123456',
 #         fecha_generacion = '2021-11-16'
@@ -164,8 +184,12 @@
 
 #     xml = nomina.toFachoXML()
 #     print(xml.tostring())
-#     assert xml.get_element('/nominaajuste:NominaIndividualDeAjuste/Eliminar/EliminandoPredecesor') is not None
-#     assert xml.get_element('/nominaajuste:NominaIndividualDeAjuste/Reemplazar/ReemplazandoPredecesor') is None
+#      assert
+# xml.get_element('/nominaajuste:NominaIndividualDeAjuste/Eliminar/EliminandoP
+# redecesor') is not None
+#      assert
+# xml.get_element('/nominaajuste:NominaIndividualDeAjuste/Reemplazar/Reemplaza
+# ndoPredecesor') is None
 
 # def test_adicionar_eliminar_devengado_comprobante_total():
 #     nomina = fe.nomina.DIANNominaIndividualDeAjuste.Eliminar()
@@ -182,12 +206,16 @@
 
 #     xml = nomina.toFachoXML()
 
-#     assert xml.get_element_text('/nominaajuste:NominaIndividualDeAjuste/Eliminar/ComprobanteTotal') == '1000000.00'
+#      assert
+# xml.get_element_text('/nominaajuste:NominaIndividualDeAjuste/Eliminar/Compro
+# banteTotal') == '1000000.00'
 
 # def test_adicionar_eliminar_asignar_predecesor():
 #     nomina = fe.nomina.DIANNominaIndividualDeAjuste.Eliminar()
 
-#     nomina.asignar_predecesor(fe.nomina.DIANNominaIndividualDeAjuste.Eliminar.Predecesor(
+#
+# nomina.asignar_predecesor(fe.nomina.DIANNominaIndividualDeAjuste.Eliminar.Pr
+# edecesor(
 #         numero = '123456',
 #         cune = 'ABC123456',
 #         fecha_generacion = '2021-11-16'
@@ -195,9 +223,15 @@
 
 #     xml = nomina.toFachoXML()
 #     print(xml.tostring())
-#     assert xml.get_element_text_or_attribute('/nominaajuste:NominaIndividualDeAjuste/Eliminar/EliminandoPredecesor/@NumeroPred') == '123456'
-#     assert xml.get_element_text_or_attribute('/nominaajuste:NominaIndividualDeAjuste/Eliminar/EliminandoPredecesor/@CUNEPred') == 'ABC123456'
-#     assert xml.get_element_text_or_attribute('/nominaajuste:NominaIndividualDeAjuste/Eliminar/EliminandoPredecesor/@FechaGenPred') == '2021-11-16'
+#      assert
+# xml.get_element_text_or_attribute('/nominaajuste:NominaIndividualDeAjuste/El
+# iminar/EliminandoPredecesor/@NumeroPred') == '123456'
+#      assert
+# xml.get_element_text_or_attribute('/nominaajuste:NominaIndividualDeAjuste/El
+# iminar/EliminandoPredecesor/@CUNEPred') == 'ABC123456'
+#      assert
+# xml.get_element_text_or_attribute('/nominaajuste:NominaIndividualDeAjuste/El
+# iminar/EliminandoPredecesor/@FechaGenPred') == '2021-11-16'
 
 # def test_nomina_devengado_horas_extras_diarias():
 #     nomina = fe.nomina.DIANNominaIndividual()