// CheckFilterKey determines whether the filter key is valid or not.
CheckFilterKey determines whether the filter key is valid or not.
// CheckFilterKey determines whether the filter key is valid or not .
func CheckFilterKey(k, _ string) error {
	switch k {
	case "", "email":
		return nil
	}
	return httpflow.ErrInvalidFilterKey
}
func CheckFilterKey ( k , _ string ) error { switch k { case " " , " " : return nil } return httpflow . ErrInvalidFilterKey }
CheckFilterKey determines whether the filter key is valid or not.
CheckFilterKey determines whether the filter key is valid or not .