code: def model(self, name=None, model=None, mask=None, **kwargs):
          
          if isinstance(model, (flask_marshmallow.Schema, flask_marshmallow.base_fields.FieldABC)):
              if not name:
                  name = model.__class__.__name__
              api_model = Model(name, model, mask=mask)
              api_model.__apidoc__ = kwargs
              return self.add_model(name, api_model)
          return super(Namespace, self).model(name=name, model=model, **kwargs)
docs: Model registration decorator.