uri.go
func (u *URI) SetHost(host string) {
	u.host = append(u.host[:0], host...)
	lowercaseBytes(u.host)
}
func (u *URI) SetHost(host string) {
	u.host = append(u.host[:0], host...)
	lowercaseBytes(u.host)
}
// SetHost sets host for the uri.