code: def test_quotient_graph_complete_bipartite():
      """Tests that the quotient graph of the complete bipartite graph under
      the "same neighbors" node relation is `K_2`.
  
      """
      G = nx.complete_bipartite_graph(2, 3)
      # Two nodes are equivalent if they are not adjacent but have the same
      # neighbor set.
  
      def same_neighbors(u, v):
          return u not in G[v] and v not in G[u] and G[u] == G[v]
  
      expected = nx.complete_graph(2)
      actual = nx.quotient_graph(G, same_neighbors)
      # It won't take too long to run a graph isomorphism algorithm on such
      # small graphs.
      assert nx.is_isomorphic(expected, actual)
  
imports: import pytest
  import networkx
  from networkx.utils import arbitrary_element, edges_equal, nodes_equal
label_desc: Use image node_id 2 for calling a global function with example usage: test_quotient_graph_complete_bipartite() and returns: unknown