code: def test_4(self):
      identified_estimand = identify_effect_id(
          build_graph_from_str("digraph{T->Y;T->X1;X1->Y;}"),
          action_nodes=["T"],
          outcome_nodes=["Y"],
      )
  
      # Compare with ground truth
      identified_str = identified_estimand.__str__()
      gt_str = (
          "Sum over {X1}:\n\tPredictor: P(Y|T,X1)\n\tPredictor: P(X1|T)"
      )
      assert identified_str == gt_str
  
file_path: dowhy/tests/causal_identifiers/test_id_identifier.py
imports: import pytest
  from dowhy import identify_effect_id
  from dowhy.graph import build_graph_from_str
label_desc: Use image node_id 4 for calling the TestIDIdentifier obj's underlying member method code with example usage: obj.test_4() without return types