code: func loginForm(w http.ResponseWriter, r *http.Request) {
  	values := r.URL.Query()
  	linkingToken := values.Get("account_linking_token")
  	redirectURI := values.Get("redirect_uri")
  	fmt.Fprint(w, templateLogin(loginPath, linkingToken, redirectURI, false))
  }
docs: // loginForm is the endpoint responsible to displays a login
  // form. During the account linking process, after clicking on the
  // login button, users are directed to this form where they are
  // supposed to sign into their account. When the form is submitted,
  // credentials are sent to the login endpoint.