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