def get_matching(delta):
    """
    Some minimal example that still is interesting, e.g.
      –––
      –––
    ––– –––
        –––
    """
    length = .95 * delta
    gap = .2 * delta
    start0, end0 = 0, length
    start1, end1 = .5 * length, 1.5 * length
    start2, end2 = length + gap, 2 * length + gap
    matching = [(0, 1), (2, 3), (4, 5), (6, 7), (8, 9)]
    filtration = [start0, end0, start1, end1, start1, end1, start2, end2, start2, end2]
    return matching, filtration