code: def test_4_cycle(self):
      # 4-cycle
      G = nx.Graph([(0, 1), (1, 2), (2, 3), (3, 0)])
      dist, path = nx.single_source_bellman_ford(G, 0)
      assert dist == {0: 0, 1: 1, 2: 2, 3: 1}
      assert path[0] == [0]
      assert path[1] == [0, 1]
      assert path[2] in [[0, 1, 2], [0, 3, 2]]
      assert path[3] == [0, 3]
  
      pred, dist = nx.bellman_ford_predecessor_and_distance(G, 0)
      assert pred[0] == []
      assert pred[1] == [0]
      assert pred[2] in [[1, 3], [3, 1]]
      assert pred[3] == [0]
      assert dist == {0: 0, 1: 1, 2: 2, 3: 1}
  
      pred, dist = nx.goldberg_radzik(G, 0)
      assert pred[0] is None
      assert pred[1] == 0
      assert pred[2] in [1, 3]
      assert pred[3] == 0
      assert dist == {0: 0, 1: 1, 2: 2, 3: 1}
  
imports: import pytest
  import networkx
  from networkx.utils import pairwise
label_desc: Use image node_id 16 for calling the TestBellmanFordAndGoldbergRadzik obj's underlying member method code with example usage: obj.test_4_cycle() without return types