code: def plot_difference_matplotlib(mdiff, title="", annotation=None):
      """Helper function to plot difference between models.
  
      Uses matplotlib as the backend."""
      import matplotlib.pyplot as plt
  
      fig, ax = plt.subplots(figsize=(18, 14))
      data = ax.imshow(mdiff, cmap="RdBu_r", origin="lower")
      plt.title(title)
      plt.colorbar(data)
  
file_path: gensim/docs/src/gallery/howtos/run_compare_lda.py
imports: import logging
  from string import punctuation
  from nltk import RegexpTokenizer
  from nltk.stem.porter import PorterStemmer
  from nltk.corpus import stopwords
  from sklearn.datasets import fetch_20newsgroups
  from gensim.corpora import Dictionary
  from gensim.models import LdaMulticore
  import numpy
label_desc: Use image node_id 3 for calling a global function with example usage: plot_difference_matplotlib(mdiff, title, annotation) without return types