docstr: Betweenness Centrality Subset: Normalized P2
  if n <= 2:  no normalization, betweenness centrality should be 0 for all nodes.
docstr_tok: ["Betweenness","Centrality","Subset",":","Normalized","P2","if","n","<","=","2",":","no","normalization",",","betweenness","centrality","should","be","0","for","all","nodes","."]
code: def test_normalized_p2(self):
      """
      Betweenness Centrality Subset: Normalized P2
      if n <= 2:  no normalization, betweenness centrality should be 0 for all nodes.
      """
      G = nx.Graph()
      nx.add_path(G, range(2))
      b_answer = {0: 0, 1: 0.0}
      b = nx.betweenness_centrality_subset(
          G, sources=[0], targets=[1], normalized=True, weight=None
      )
      for n in sorted(G):
          assert b[n] == pytest.approx(b_answer[n], abs=1e-7)
  
imports: import pytest
  import networkx
label_desc: Use image node_id 9 for calling the TestSubsetBetweennessCentrality obj's underlying member method code with example usage: obj.test_normalized_p2() without return types