code: def test_normalized_laplacian(example_graph):
      Aadj = example_graph.to_adjacency_matrix()
      laplacian = normalized_laplacian(Aadj).todense()
      eigenvalues, _ = np.linalg.eig(laplacian)
  
      # min eigenvalue of normalized laplacian is 0
      # max eigenvalue of normalized laplacian is <= 2
      assert eigenvalues.min() == pytest.approx(0, abs=1e-7)
      assert eigenvalues.max() <= (2 + 1e-7)
      assert laplacian.shape == Aadj.get_shape()
  
      # Sum of laplacian is equal to the number of degree 0 nodes
      laplacian = normalized_laplacian(Aadj, symmetric=False)
      num_degree_zero_nodes = (Aadj.sum(axis=1) == 0).sum()
      assert num_degree_zero_nodes == pytest.approx(
          laplacian.sum(), abs=1e-7
      )
      assert laplacian.get_shape() == Aadj.get_shape()
  
file_path: stellargraph/tests/core/test_utils.py
imports: import pytest
  import numpy
  from stellargraph.core.utils import *
  from ..test_utils import flaky_xfail_mark
  from ..test_utils.graphs import example_graph_random
label_desc: Use image node_id 13 for calling a global function with example usage: test_normalized_laplacian(example_graph) without return types