code: def test_problematic_graph_issue_2381(self, method):
      pytest.importorskip("scipy")
      G = nx.path_graph(4)
      G.add_edges_from([(4, 2), (5, 1)])
      A = nx.laplacian_matrix(G)
      sigma = 0.438447187191
      ac = nx.algebraic_connectivity(G, tol=1e-12, method=method)
      assert ac == pytest.approx(sigma, abs=1e-7)
      x = nx.fiedler_vector(G, tol=1e-12, method=method)
      check_eigenvector(A, sigma, x)
  
imports: from math import sqrt
  import pytest
  import networkx
label_desc: Use image node_id 9 for calling the TestAlgebraicConnectivity obj's underlying member method code with example usage: obj.test_problematic_graph_issue_2381(method) without return types