code: def patch_view_model(view_cls, model_cls):
      
      original_model = view_cls.Model
      view_cls.Model = model_cls
  
      try:
          yield
      finally:
          view_cls.Model = original_model
docs: Patches view_cls.Model with model_cls.
  
      :param view_cls: View class "Model" param of which should be
          patched
      :param model_cls: Model class which should be used to patch
          view_cls.Model