LukasMeine / vigilance

  if (typeof fn !== 'function') {

    throw new TypeError('"callback" argument must be a function');

  }

  var len = arguments.length;

  var args, i;

  switch (len) {

  case 0:

  case 1:

    return process.nextTick(fn);

  case 2:

    return process.nextTick(function afterTickOne() {

      fn.call(null, arg1);

    });

  case 3:

    return process.nextTick(function afterTickTwo() {

      fn.call(null, arg1, arg2);

    });

  case 4:

    return process.nextTick(function afterTickThree() {

      fn.call(null, arg1, arg2, arg3);

    });

  default:

    args = new Array(len - 1);

    i = 0;

    while (i < args.length) {

      args[i++] = arguments[i];

    }

    return process.nextTick(function afterTick() {

      fn.apply(null, args);

    });

  }

}