code: func (p *WebPage) SetCookies(cookies []*http.Cookie) error {
  	a := make([]cookieJSON, len(cookies))
  	for i := range cookies {
  		a[i] = encodeCookieJSON(cookies[i])
  	}
  	req := map[string]interface{}{"ref": p.ref.id, "cookies": a}
  	return p.ref.process.doJSON("POST", "/webpage/SetCookies", req, nil)
  }
docs: // SetCookies sets a list of cookies visible to the current URL.