code: def test_undirected_node_contraction_no_copy():
      """Tests for node contraction in an undirected graph
      by making changes in place."""
      G = nx.cycle_graph(4)
      actual = nx.contracted_nodes(G, 0, 1, copy=False)
      expected = nx.cycle_graph(3)
      expected.add_edge(0, 0)
      assert nx.is_isomorphic(actual, G)
      assert nx.is_isomorphic(actual, expected)
  
imports: import pytest
  import networkx
  from networkx.utils import arbitrary_element, edges_equal, nodes_equal
label_desc: Use image node_id 21 for calling a global function with example usage: test_undirected_node_contraction_no_copy() without return types