code: func (h *Handler) renderUserInvite(w http.ResponseWriter, r *http.Request, p httprouter.Params) (interface{}, error) {
  	token := p[0].Value
  	user, qrCodeBytes, err := h.auth.GetUserInviteInfo(token)
  	if err != nil {
  		return nil, trace.Wrap(err)
  	}
  
  	return &renderUserInviteResponse{
  		InviteToken: token,
  		User:        user,
  		QR:          qrCodeBytes,
  	}, nil
  }
docs: // renderUserInvite is called to show user the new user invitation page
  //
  // GET /v1/webapi/users/invites/:token
  //
  // Response:
  //
  // {"invite_token": "token", "user": "alex", qr: "base64-encoded-qr-code image"}
  //
  //