code: def add_number_label(ax, classes, matrix, cmap, plot_lib):
      """
      Add number labels to confusion matrix plot.
  
      :param ax: confusion matrix axes
      :type ax: matplotlib.axes
      :param classes: confusion matrix classes
      :type classes: list
      :param matrix: the confusion matrix in array form
      :type matrix: numpy.array
      :param cmap: color map
      :type cmap: matplotlib.colors.ListedColormap
      :param plot_lib: plotting library
      :type plot_lib: str
      :return: None
      """
      diff_matrix = float(matrix.max()) - matrix
      diff_matrix_max = float(diff_matrix.max())
      for i in range(len(classes)):
          for j in range(len(classes)):
              color_index = float(
                  round(diff_matrix[i][j] / diff_matrix_max)
              )
              color = cmap(color_index)
              x = j
              y = i
              if plot_lib == "seaborn":
                  x += 0.5
                  y += 0.5
              ax.text(
                  x,
                  y,
                  str(matrix[i][j]),
                  horizontalalignment="center",
                  verticalalignment="center",
                  color=color,
              )
  
imports: from __future__ import division
  import sys
  import math
  import numpy
  import re
  from .pycm_param import *
  from .pycm_error import pycmMatrixError
  from warnings import warn
  from functools import wraps
label_desc: Use image node_id 23 for calling a global function with example usage: add_number_label(ax, classes, matrix, cmap, plot_lib) without return types