code: def test_sort_one(self):
      rootnode = "root"
      node2 = "node2"
      node3 = "node3"
      node4 = "node4"
      subnode1 = "subnode1"
      subnode2 = "subnode2"
      subnode3 = "subnode3"
      subnode4 = "subnode4"
      subsubnode1 = "subsubnode1"
      tuples = [
          (subnode3, subsubnode1),
          (node2, subnode1),
          (node2, subnode2),
          (rootnode, node2),
          (rootnode, node3),
          (rootnode, node4),
          (node4, subnode3),
          (node4, subnode4),
      ]
      self.assert_sort(tuples)
  
imports: from sqlalchemy import exc
  from sqlalchemy.testing import assert_raises
  from sqlalchemy.testing import eq_
  from sqlalchemy.testing import fixtures
  from sqlalchemy.testing.util import conforms_partial_ordering
  from sqlalchemy.util import topological
label_desc: Use image node_id 4 for calling the DependencySortTest obj's underlying member method code with example usage: obj.test_sort_one() without return types