with-promise-or-bluebird.js

var Promise = require('native-or-bluebird');

var callbackOrPromise = function (cb, fn) {
  if (cb) {
    return fn(cb);
  }
  return new Promise(function (resolve, reject) {
    fn(function (err, res) {
      err ? reject(err) : resolve(res);
    });
  });
};