code: 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
  
imports: import pytest
  from flash.core.serve.dag.order import ndependencies, order
  from flash.core.serve.dag.task import get, get_deps
  from flash.core.serve.dag.utils_test import add, inc
  from flash.core.utilities.imports import _TOPIC_SERVE_AVAILABLE
label_desc: Use image node_id 6 for calling a global function with example usage: test_base_of_reduce_preferred(abcde) without return types