code: def test_heatmap(explainer):
      """Make sure the heatmap plot is unchanged."""
      fig = plt.figure()
      shap_values = explainer(explainer.data)
      shap.plots.heatmap(shap_values, show=False)
      plt.tight_layout()
      return fig
  
imports: import matplotlib.pyplot
  import numpy
  import pytest
  import shap
label_desc: Use image node_id 1 for calling a global function with example usage: test_heatmap(explainer) and returns: fig