function Timer(delay, callbacks){
  if (Object.prototype.toString.call(callbacks) === "[object Function]") {
    callbacks = [callbacks];
  }
  this.callbacks = callbacks;
  var that = this;
  var id = setInterval(function tick(){
    if (!that.running) return;
    for (var i=0; i<that.callbacks.length; i++) {
      that.callbacks[i].call(that);
    }
    that.count++;
  }, delay);
  this.__defineGetter__('id', function(){return id});
  this.__defineGetter__('delay', function(){return delay});
  Timer.all.push(this);
}
Timer.prototype.running = true;
Timer.prototype.count = 0;
Timer.prototype.pause = function pause(){
  this.running = false;
  return this;
};
Timer.prototype.run = function run(){
  this.running = true;
  return this;
};
Timer.prototype.stop = function stop(){
  // Unlike pause, once you stop timer, you can't run it again
  clearInterval(this.id);
  this.stopped = true;
  return this;
};

Timer.all = [];
Timer.all.pause = function pause(){
  var all = Timer.all;
  for (var i=0; i<all.length; i++) {
    all[i].pause();
  }
  return all;
};
Timer.all.run = function run(){
  var all = Timer.all;
  for (var i=0; i<all.length; i++) {
    all[i].run();
  }
  return all;
};
Timer.all.stop = function stop(){
  var all = Timer.all;
  for (var i=0; i<all.length; i++) {
    all[i].stop();
  }
  return all;
};