code: def test_collider_graph_dsep(collider_graph):
      """Example-based test of d-separation for collider_graph."""
      assert nx.is_d_separator(collider_graph, {0}, {1}, set())
      assert not nx.is_d_separator(collider_graph, {0}, {1}, {2})
  
imports: from itertools import combinations
  import pytest
  import networkx
label_desc: Use image node_id 19 for calling a global function with example usage: test_collider_graph_dsep(collider_graph) without return types