code: def uuid(uuid_value=None):
          
          if uuid_value:
              if not validate_uuid(uuid_value):
                  raise ValueError(
                      "uuid_value must be a valid UUID version 4 object")
          else:
              uuid_value = uuid.uuid4()
  
          if versions_settings.VERSIONS_USE_UUIDFIELD:
              return uuid_value
          else:
              return six.u(str(uuid_value))
docs: Returns a uuid value that is valid to use for id and identity fields.
  
          :return: unicode uuid object if using UUIDFields, uuid unicode string
              otherwise.