code: def test_path_graph_dsep(path_graph):
      """Example-based test of d-separation for path_graph."""
      assert nx.is_d_separator(path_graph, {0}, {2}, {1})
      assert not nx.is_d_separator(path_graph, {0}, {2}, set())
  
imports: from itertools import combinations
  import pytest
  import networkx
label_desc: Use image node_id 17 for calling a global function with example usage: test_path_graph_dsep(path_graph) without return types