code: def test_absent_source_bellman_ford(self):
      # the check is in _bellman_ford; this provides regression testing
      # against later changes to "client" Bellman-Ford functions
      G = nx.path_graph(2)
      for fn in (
          nx.bellman_ford_predecessor_and_distance,
          nx.bellman_ford_path,
          nx.bellman_ford_path_length,
          nx.single_source_bellman_ford_path,
          nx.single_source_bellman_ford_path_length,
          nx.single_source_bellman_ford,
      ):
          pytest.raises(nx.NodeNotFound, fn, G, 3, 0)
          pytest.raises(nx.NodeNotFound, fn, G, 3, 3)
  
imports: import pytest
  import networkx
  from networkx.utils import pairwise
label_desc: Use image node_id 2 for calling the TestBellmanFordAndGoldbergRadzik obj's underlying member method code with example usage: obj.test_absent_source_bellman_ford() without return types