docs: def _to_dict(self):
          """Return a json dictionary representing this model."""
          _dict = {}
          if hasattr(self,
                     'customization_id') and self.customization_id is not None:
              _dict['customization_id'] = self.customization_id
          if hasattr(self, 'name') and self.name is not None:
              _dict['name'] = self.name
          if hasattr(self, 'language') and self.language is not None:
              _dict['language'] = self.language
          if hasattr(self, 'owner') and self.owner is not None:
              _dict['owner'] = self.owner
          if hasattr(self, 'created') and self.created is not None:
              _dict['created'] = self.created
          if hasattr(self, 'last_modified') and self.last_modified is not None:
              _dict['last_modified'] = self.last_modified
          if hasattr(self, 'description') and self.description is not None:
              _dict['description'] = self.description
          if hasattr(self, 'words') and self.words is not None:
              _dict['words'] = [x._to_dict() for x in self.words]
          return _dict