code: def test_causal_estimator_placeholder_methods():
      estimator = MockEstimator(None)
      with pytest.raises(NotImplementedError):
          estimator._do(None)
      with pytest.raises(NotImplementedError):
          estimator.construct_symbolic_estimator(None)
  
file_path: dowhy/tests/test_causal_estimator.py
imports: import unittest
  import pytest
  from dowhy.causal_estimator import CausalEstimator
label_desc: Use image node_id 1 for calling a global function with example usage: test_causal_estimator_placeholder_methods() without return types