code: def test_predecessor_cycle(self):
      G = nx.cycle_graph(4)
      pred = nx.predecessor(G, 0)
      assert pred[0] == []
      assert pred[1] == [0]
      assert pred[2] in [[1, 3], [3, 1]]
      assert pred[3] == [0]
  
file_path: networkx/networkx/algorithms/shortest_paths/tests/test_unweighted.py
imports: import pytest
  import networkx
label_desc: Use image node_id 12 for calling the TestUnweightedPath obj's underlying member method code with example usage: obj.test_predecessor_cycle() without return types