code: def __get_arg(cls, kwds, kwd):
      
      alt_kwd = '_' + kwd
      if alt_kwd in kwds:
        return kwds.pop(alt_kwd)
      if kwd in kwds:
        obj = getattr(cls, kwd, None)
        if not isinstance(obj, Property) or isinstance(obj, ModelKey):
          return kwds.pop(kwd)
      return None
docs: Internal helper method to parse keywords that may be property names.