http.go
func (resp *Response) WriteTo(w io.Writer) (int64, error) {
	return writeBufio(resp, w)
}
func (resp *Response) WriteTo(w io.Writer) (int64, error) {
	return writeBufio(resp, w)
}
func ( resp * Response ) WriteTo ( w io . Writer ) ( int64 , error ) { return writeBufio ( resp , w ) }
// WriteTo writes response to w. It implements io.WriterTo.
WriteTo writes response to w . It implements io . WriterTo .