code: def test_elbow_plot(lsi_model, nmf_model):
      assert isinstance(
          lsi_model.elbow_plot(), matplotlib.axes._subplots.Axes
      ), "Elbow plot is not of the expected return type of a Matplotlib Plot"
      with pytest.raises(ValueError):
          nmf_model.elbow_plot(), "Elbow plot function incorrectly runs for topic model that is not an LDA or LSA/LSI model"
  
imports: import pandas
  import numpy
  import matplotlib
  import sklearn
  import pytest
  from data_describe.text.topic_modeling import topic_model
label_desc: Use image node_id 15 for calling a global function with example usage: test_elbow_plot(lsi_model, nmf_model) without return types