Function callbackify

lib/index.es.js:7847–7856

(fun)

}

function callbackify(fun) {
  return function (...args) {
    var cb = args.pop();
    var promise = fun.apply(this, args);
    if (typeof cb === 'function') {
      promisedCallback(promise, cb);
    }
    return promise;
  };
}

// Promise finally util similar to Q.finally
function fin(promise, finalPromiseFactory) {