code: def test_missing_immediate_doms(self):
      # see https://github.com/networkx/networkx/issues/2070
      g = nx.DiGraph()
      edges = [
          ("entry_1", "b1"),
          ("b1", "b2"),
          ("b2", "b3"),
          ("b3", "exit"),
          ("entry_2", "b3"),
      ]
  
      # entry_1
      #   |
      #   b1
      #   |
      #   b2  entry_2
      #    |  /
      #    b3
      #    |
      #   exit
  
      g.add_edges_from(edges)
      # formerly raised KeyError on entry_2 when parsing b3
      # because entry_2 does not have immediate doms (no path)
      nx.dominance_frontiers(g, "entry_1")
  
imports: import pytest
  import networkx
label_desc: Use image node_id 12 for calling the TestDominanceFrontiers obj's underlying member method code with example usage: obj.test_missing_immediate_doms() without return types