function(event, func) {
    this._events = this._events || {};
    if (event in this._events === false) return;
    this._events[event].splice(this._events[event].indexOf(func), 1);
  }
function(event, func) {
    this._events = this._events || {};
    if (event in this._events === false) return;
    this._events[event].splice(this._events[event].indexOf(func), 1);
  }
function ( event , func ) { this . _events = this . _events || { } ; if ( event in this . _events === false ) return ; this . _events [ event ] . splice ( this . _events [ event ] . indexOf ( func ) , 1 ) ; }
Remove custom event listener
@param  {String} event Event type
@param  {Function} func   Callback
@return {Void}
Remove custom event listener