code: def get_manager(self, model):
          
          if isinstance(model, six.string_types):
              # undocumented string lookup
              for k, m in self._manager_map.items():
                  if k.__name__ == model:
                      return m
              else:
                  raise KeyError(model)
  
          return self._manager_map[model]
docs: Return the active manager for the given model.
          :param model: Model class to look up the manager instance for.
          :return: Manager instance for the model associated with this client.