docs: function(type, listener, useCapture) {
  			if (!this._eventTypes) { this._eventTypes = {}; }
  			var state = this._eventTypes[type];
  			if (!state) {
  				state = this._eventTypes[type] = {level: 0, listeners: []};
  			}
  			var listeners = state.listeners;
  			listeners.push({listener: listener, useCapture: useCapture});
  		}