code: def example_frontdoor_graph_solution(request):
      return IdentificationTestFrontdoorGraphSolution(
          **TEST_FRONTDOOR_GRAPH_SOLUTIONS[request.param]
      )
  
file_path: dowhy/tests/causal_identifiers/base.py
imports: import pytest
  from dowhy.graph import build_graph_from_str
  from .example_graphs import TEST_FRONTDOOR_GRAPH_SOLUTIONS, TEST_GRAPH_SOLUTIONS
label_desc: Use image node_id 2 for calling a global function with example usage: example_frontdoor_graph_solution(request) and returns: IdentificationTestFrontdoorGraphSolution