code: def test_reg_externalsource_index_exists(
      regression_explainer_with_external_data,
  ):
      assert regression_explainer_with_external_data.index_exists("0")
      assert regression_explainer_with_external_data.index_exists("100")
      assert regression_explainer_with_external_data.index_exists("160")
      assert regression_explainer_with_external_data.index_exists(0)
  
      assert not regression_explainer_with_external_data.index_exists(
          -1
      )
      assert not regression_explainer_with_external_data.index_exists(
          120
      )
      assert not regression_explainer_with_external_data.index_exists(
          "wrong index"
      )
  
imports: import pytest
  import pandas
  from explainerdashboard.explainers import ClassifierExplainer, RegressionExplainer
  from explainerdashboard.datasets import titanic_survive, titanic_fare
label_desc: Use image node_id 19 for calling a global function with example usage: test_reg_externalsource_index_exists(regression_explainer_with_external_data) without return types