[account_taken]

These kinds problems can easily be solved with promises too. It would be even simpler if `fs.stat` returned a promise and there are promise libraries that do that. Promises is a small library I use, probably about the same number of bytes as your library, as I transition my code from callbacks to promises.

      var queue = new Promises;
      fs.stat("file1.txt", queue.cb());
      fs.stat("file2.txt", queue.cb());
      fs.stat("file2.txt", queue.cb());
      queue.all()
        .then()
        .fail();

But, comparing how promises solves the same flow as callbacks misses the point. Here's an example where an action is taken when two events fire (promises shine here):

      pub.on('foo', function() {
        promise1.fulfill();
      });
      pub.on('bar', function() {
        promise2.fullfill();
      });
      Vow.all([promise1, promise2]).then(...).fail(...);