Extend typescript for custom post type

[IRediTOTO]

Hi, I am trying to extend WpAPI type but I don't know how. I created some custom post type like this

import WPAPI from "wpapi";

const _wpPrivate = new WPAPI({
  endpoint: `${process.env.BLITZ_PUBLIC_WP_BASE_URL}/wp-json`,
  username: process.env.WP_USERNAME,
  password: process.env.WP_PASSWORD,
});
_wpPrivate.deals = _wpPrivate.registerRoute("wp/v2", "/deal/(?P<id>)");

export const wpPrivate = _wpPrivate;

But type auto complete not work. How can I do that ?