code: def setup_class(cls):
      HistoricalTests.setup_class()
      cls.G = nx.DiGraph
  
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 1 for calling the TestDiGraphHistorical obj's underlying member method code with example usage: obj.setup_class(cls) without return types