def test_base_of_reduce_preferred(abcde):
    r"""Testing structure.

              a3

              /|
            a2 |
           /|  |
         a1 |  |
        /|  |  |
      a0 |  |  |
      |  |  |  |
      b0 b1 b2 b3
        \ \ / /
           c

    We really want to run b0 quickly

    """
    a, b, c, d, e = abcde
    dsk = {(a, i): (f, (a, i - 1), (b, i)) for i in [1, 2, 3]}
    dsk[(a, 0)] = (f, (b, 0))
    dsk.update({(b, i): (f, c, 1) for i in [0, 1, 2, 3]})
    dsk[c] = 1

    o = order(dsk)

    assert o[(b, 0)] <= 4
    assert o[(b, 1)] <= 6
Testing structure.

              a3

              /|
            a2 |
           /|  |
         a1 |  |
        /|  |  |
      a0 |  |  |
      |  |  |  |
      b0 b1 b2 b3
        \ \ / /
           c

    We really want to run b0 quickly

    
tests/core/serve/test_dag/test_order.py