code: def from_form(self, param_name, field):
          
          return self.__from_source(param_name, field, lambda: request.form, 'form')
docs: A decorator that converts a request form into a function parameter based on the specified field.
  
          :param str param_name: The parameter which receives the argument.
          :param Field field: The field class or instance used to deserialize the request form to a Python object.
          :return: A function