isLooping() {
    if (!this.bufferSourceNode) {
      return false;
    }
    if (this._looping === true && this.isPlaying() === true) {
      return true;
    }
    return false;
  }
Returns 'true' if a p5.SoundFile is currently looping and playing, 'false' if not.

@method isLooping
@for p5.SoundFile
@return {Boolean}