code: def test_find_multiple_cycles_four(self):
      tuples = [
          ("node6", "node2"),
          ("node15", "node19"),
          ("node19", "node2"),
          ("node4", "node10"),
          ("node15", "node13"),
          ("node17", "node11"),
          ("node1", "node19"),
          ("node15", "node8"),
          ("node6", "node20"),
          ("node14", "node11"),
          ("node6", "node14"),
          ("node11", "node2"),
          ("node10", "node20"),
          ("node1", "node11"),
          ("node20", "node19"),
          ("node4", "node20"),
          ("node15", "node20"),
          ("node9", "node19"),
          ("node11", "node10"),
          ("node11", "node19"),
          ("node13", "node6"),
          ("node3", "node15"),
          ("node9", "node11"),
          ("node4", "node17"),
          ("node2", "node20"),
          ("node19", "node10"),
          ("node8", "node4"),
          ("node11", "node3"),
          ("node6", "node1"),
      ]
      allnodes = ["node%d" % i for i in range(1, 21)]
      eq_(
          topological.find_cycles(tuples, allnodes),
          {
              "node11",
              "node10",
              "node13",
              "node15",
              "node14",
              "node17",
              "node19",
              "node20",
              "node8",
              "node1",
              "node3",
              "node2",
              "node4",
              "node6",
          },
      )
  
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 18 for calling the DependencySortTest obj's underlying member method code with example usage: obj.test_find_multiple_cycles_four() without return types