uri.go
func (u *URI) Parse(host, uri []byte) {
	u.parse(host, uri, nil)
}
func (u *URI) Parse(host, uri []byte) {
	u.parse(host, uri, nil)
}
// Parse initializes URI from the given host and uri.
//
// host may be nil. In this case uri must contain fully qualified uri,
// i.e. with scheme and host. http is assumed if scheme is omitted.
//
// uri may contain e.g. RequestURI without scheme and host if host is non-empty.