Function callback

lib/utils/helpers.js:216–233

(err, result)

  if (typeof done !== "function") { done = function() {}; }

  function callback(err, result) {
    if (error) {
      return;
    }

    if (err || error) {
      error = err;
      done(err);
      return;
    }

    completed++;
    results.push(result);

    if (completed === total) {
      done(null, results);
    }
  }

  if (!functions.length) { done(); }