code: def validate_field(cls,
                     field_name,
                     *validation_func,  # type: ValidationFuncs
                     **kwargs):
      # type: (...) -> Callable
      
      return decorate_cls_with_validation(cls, field_name, *validation_func, **kwargs)
docs: A class decorator. It goes through all class variables and for all of those that are descriptors with a __set__,
      it wraps the descriptors' setter function with a `validate_arg` annotation
  
      :param field_name:
      :param validation_func:
      :param help_msg:
      :param error_type:
      :param none_policy:
      :param kw_context_args:
      :return