onLooped(fromSegment, toSegment) {
    if (fromSegment.reachable && toSegment.reachable) {
      this.emitter.emit(
        'onCodePathSegmentLoop',
        fromSegment,
        toSegment,
        this.currentNode,
      );
    }
  }
This is called on a code path looped.
Then this raises a looped event.
@param {CodePathSegment} fromSegment A segment of prev.
@param {CodePathSegment} toSegment A segment of next.
@returns {void}