'Internal helper method to parse keywords that may be property names.'

@classmethod
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
