code: def instances(self, skip_exist_test=False):
          
          self.reset_result_type()
          self._instances = True
          self._instances_skip_exist_test = skip_exist_test
          return self
docs: Ask the collection to return a list of instances.
          If skip_exist_test is set to True, the instances returned by the
          collection won't have their primary key checked for existence.