code: def register(cls, use_admin=True):
      
      with app.app_context():
          if getattr(current_app, 'class_references', None) is None:
              current_app.class_references = {}
          if isinstance(cls, (list, tuple)):
              for entry in cls:
                  register_internal_data(entry)
                  entry.use_admin = use_admin
          else:
              register_internal_data(cls)
              cls.use_admin = use_admin
docs: Register with the API a :class:`sandman.model.Model` class and
      associated endpoint.
  
      :param cls: User-defined class derived from :class:`sandman.model.Model` to
                  be registered with the endpoint returned by :func:`endpoint()`
      :type cls: :class:`sandman.model.Model` or tuple