add items for selection lists

product.py

@@ -7,10 +7,22 @@ from trytond.model import fields
 
 __all__ = ['Product']
 
-_RISK = [(None, '')]
-_USE = [(None, '')]
-_BIOMEDICAL_CLASS = [(None, '')]
-_MAIN_TECNOLOGY = [(None, '')]
+_RISK = [('uno', 'I'),
+         ('dosA', 'IIA'),
+         ('dosB', 'IIB')]
+
+_USE = [('medico', 'Médico'),
+        ('basico', 'Basico'),
+        ('apoyo', 'Apoyo')]
+
+_BIOMEDICAL_CLASS = [('diagnostico', 'Diagnóstico'),
+                     ('rehabilitación', 'Rehabilitación')]
+
+_MAIN_TECNOLOGY = [('mecanico', 'Mecánico'),
+                   ('electrico', 'Electrico'),
+                   ('electronico', 'Electrónico'),
+                   ('hidraulico', 'Hidraulico'),
+                   ('neumatico', 'Neumatico')]
 
 class Product(ModelSQL, ModelView, metaclass=PoolMeta):
     'Product'

purchase.py

@@ -1,6 +1,5 @@
 #This file is part of Tryton.  The COPYRIGHT file at the top level of
 #txhis repository contains the full copyright notices and license terms
-
 from trytond.model import ModelView, ModelSQL