def METHOD_NAME(params):
    hypothesiser = params["hypothesiser"]
    all_tracks = params["all_tracks"]
    start_time = params["start"]
    stitcher = TrackStitcher(forward_hypothesiser=hypothesiser)
    stitched_tracks, _ = stitcher.stitch(all_tracks, start_time)
    no_stitched_tracks = len(stitched_tracks)
    assert no_stitched_tracks == 3