uri.go
func (u *URI) SetScheme(scheme string) {
	u.scheme = append(u.scheme[:0], scheme...)
	lowercaseBytes(u.scheme)
}
func (u *URI) SetScheme(scheme string) {
	u.scheme = append(u.scheme[:0], scheme...)
	lowercaseBytes(u.scheme)
}
// SetScheme sets URI scheme, i.e. http, https, ftp, etc.