code: def _get_model(self, lookup_keys, session):
          
          try:
              return self.queryset(session).filter_by(**lookup_keys).one()
          except NoResultFound:
              raise NotFoundException('No model of type {0} was found using '
                                      'lookup_keys {1}'.format(self.model.__name__, lookup_keys))
docs: Gets the sqlalchemy Model instance associated with
          the lookup keys.
  
          :param dict lookup_keys: A dictionary of the keys
              and their associated values.
          :param Session session: The sqlalchemy session
          :return: The sqlalchemy orm model instance.