code: function(control) {
        var initiatedEventId, initiatedEvent;
        return this._events.some(function (evt) {
           if (evt.eventType === "StartChildWorkflowExecutionFailed") {
              initiatedEventId = evt.startChildWorkflowExecutionFailedEventAttributes.initiatedEventId;
              initiatedEvent = this.eventById(initiatedEventId);
              if (initiatedEvent.startChildWorkflowExecutionInitiatedEventAttributes.control === control) {
                 return true;
              }
           } else if (evt.eventType === "ChildWorkflowExecutionFailed") {
              initiatedEventId = evt.childWorkflowExecutionFailedEventAttributes.initiatedEventId;
              initiatedEvent = this.eventById(initiatedEventId);
              if (initiatedEvent.startChildWorkflowExecutionInitiatedEventAttributes.control === control) {
                 return true;
              }
           }
        }, this);
     }
docs: Return true if the child workflow has failed
  @param {String} control
  @returns {Boolean}