code: def get_model_at_related_field(model, attr):
      
  
      field = model._meta.get_field(attr)
  
      if hasattr(field, 'related_model'):
          return field.related_model
  
      raise ValueError("{model}.{attr} ({klass}) is not a relationship field.".format(**{
          'model': model.__name__,
          'attr': attr,
          'klass': field.__class__.__name__,
      }))
docs: Looks up ``attr`` as a field of ``model`` and returns the related model class.  If ``attr`` is
      not a relationship field, ``ValueError`` is raised.