code: def test_successors(self):
      G = self.G()
      G.add_nodes_from("GJK")
      G.add_edges_from(
          [("A", "B"), ("A", "C"), ("B", "D"), ("B", "C"), ("C", "D")]
      )
      assert sorted(G.successors("A")) == ["B", "C"]
      assert sorted(G.successors("A")) == ["B", "C"]
      assert sorted(G.successors("G")) == []
      assert sorted(G.successors("D")) == []
      assert sorted(G.successors("G")) == []
      pytest.raises(nx.NetworkXError, G.successors, "j")
      pytest.raises(nx.NetworkXError, G.successors, "j")
  
file_path: networkx/networkx/classes/tests/test_digraph_historical.py
imports: import pytest
  import networkx
  import networkx
  from .historical_tests import HistoricalTests
label_desc: Use image node_id 6 for calling the TestDiGraphHistorical obj's underlying member method code with example usage: obj.test_successors() without return types