uri.go
func (u *URI) SetHost(host string) error {
	m := hostRegexp.FindStringSubmatch(host)
	if m == nil {
		return errors.New("invalid host")
	}
	u.host = host
	return nil
}
func (u *URI) SetHost(host string) error {
	m := hostRegexp.FindStringSubmatch(host)
	if m == nil {
		return errors.New("invalid host")
	}
	u.host = host
	return nil
}
// SetHost sets the host of this URI.