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