code: function (name, HandlerClass) {
  		if (!HandlerClass) { return this; }
  
  		var handler = this[name] = new HandlerClass(this);
  
  		this._handlers.push(handler);
  
  		if (this.options[name]) {
  			handler.enable();
  		}
  
  		return this;
  	}
docs: TODO handler.addTo