code: def test_estrada_index(self):
      answer = 1041.2470334195475
      result = estrada_index(nx.karate_club_graph())
      assert answer == pytest.approx(result, abs=1e-7)
  
file_path: networkx/networkx/algorithms/centrality/tests/test_subgraph.py
imports: import pytest
  import networkx
  from networkx.algorithms.centrality.subgraph_alg import communicability_betweenness_centrality, estrada_index, subgraph_centrality, subgraph_centrality_exp
label_desc: Use image node_id 5 for calling the TestSubgraph obj's underlying member method code with example usage: obj.test_estrada_index() without return types