function createStream() {
    const manifest = shaka.test.ManifestGenerator.generate((manifest) => {
      manifest.presentationTimeline.setDuration(60);
      manifest.addVariant(0, (variant) => {
        variant.addVideo(11, (stream) => {
          stream.useSegmentTemplate('video-11-%d.mp4', 10);
        });
      });
    });

    const videoStream = manifest.variants[0].video;
    if (!videoStream) {
      throw new Error('unexpected stream setup - variant.video is null');
    }
    return videoStream;
  }
Creates a stream.
@return {shaka.extern.Stream}