code: def test_terminal_node_backtrack():
      r"""
      https://github.com/dask/dask/issues/6745
  
      We have
  
      1. A terminal node that depends on the entire graph ('s')
      2. Some shared dependencies near the roots ('a1', 'a4')
      3. But the left and right halves are disconnected, other
         than the terminal node.
  
                         s
                 /   /       \   \
                /   /         \   \
              s00  s10       s01  s11
               |    |         |    |
              b00  b10       b01  b11
              / \  / \       / \ / \
             a0  a1  a2    a3  a4  a5
  
      Previously we started at 'a', and worked up to 's00'. We'd like to finish
      's00' completely, so we progress to 's' and work through its dependencies.
  
      Ideally, we would choose 's10', since we've already computed one of its
      (eventual) dependencies: 'a1'. However, all of 's00' through 's11' had
      equal metrics so we fell back to the name tie-breaker and started on
      's01' (via 'a3', a4', 'b01', ...).
      """
      dsk = {
          # left half
          ("a", 0): (0,),
          ("a", 1): (1,),
          ("a", 2): (2,),
          ("b", 0): (f, ("a", 0), ("a", 1)),
          ("b", 1): (f, ("a", 1), ("a", 2)),
          ("store", 0, 0): ("b", 0),
          ("store", 1, 0): ("b", 1),
          # right half
          ("a", 3): (3,),
          ("a", 4): (4,),
          ("a", 5): (5,),
          ("b", 2): (f, ("a", 3), ("a", 4)),
          ("b", 3): (f, ("a", 4), ("a", 5)),
          ("store", 0, 1): ("b", 2),
          ("store", 1, 1): ("b", 3),
          "store": (
              f,
              ("store", 0, 0),
              ("store", 1, 0),
              ("store", 0, 1),
              ("store", 1, 1),
          ),
      }
      o = order(dsk)
      assert_topological_sort(dsk, o)
      assert o[("a", 2)] < o[("a", 3)]
  
imports: from __future__ import annotations
  import inspect
  import pytest
  import dask
  from dask import delayed
  from dask.base import collections_to_dsk, key_split, visualize_dsk
  from dask.core import get_deps
  from dask.order import _connecting_to_roots, diagnostics, ndependencies, order
  from dask.utils_test import add, inc
label_desc: Use image node_id 31 for calling a global function with example usage: test_terminal_node_backtrack() without return types