code: def test_digraph1(self):
      G = nx.DiGraph([(0, 1), (0, 2), (0, 3)])
      L = nx.line_graph(G)
      # no edge graph, but with nodes
      assert L.adj == {(0, 1): {}, (0, 2): {}, (0, 3): {}}
  
imports: import pytest
  import networkx
  from networkx.generators import line
  from networkx.utils import edges_equal
label_desc: Use image node_id 4 for calling the TestGeneratorLine obj's underlying member method code with example usage: obj.test_digraph1() without return types