gorilla.go
func (m *GorillaHost) Build(u *url.URL, values url.Values) error {
	host, err := m.RevertValid(values)
	if err == nil {
		if u.Scheme == "" {
			u.Scheme = "http"
		}
		u.Host = host
	}
	return err
}
func (m *GorillaHost) Build(u *url.URL, values url.Values) error {
	host, err := m.RevertValid(values)
	if err == nil {
		if u.Scheme == "" {
			u.Scheme = "http"
		}
		u.Host = host
	}
	return err
}
// Build builds the URL host using the given positional and named variables,
// and writes it to the given URL.