code: def test_parameters(self):
      G = nx.DiGraph()
      G.add_node(0)
  
      def kernel(x):
          return x
  
      assert nx.is_isomorphic(gn_graph(1), G)
      assert nx.is_isomorphic(gn_graph(1, kernel=kernel), G)
      assert nx.is_isomorphic(gnc_graph(1), G)
      assert nx.is_isomorphic(gnr_graph(1, 0.5), G)
  
file_path: networkx/networkx/generators/tests/test_directed.py
imports: import pytest
  import networkx
  from networkx.classes import Graph, MultiDiGraph
  from networkx.generators.directed import gn_graph, gnc_graph, gnr_graph, random_k_out_graph, random_uniform_k_out_graph, scale_free_graph
label_desc: Use image node_id 3 for calling the TestGeneratorsDirected obj's underlying member method code with example usage: obj.test_parameters() and returns: x