code: def test_color_matrix(self):
      msno.matrix(
          self.simple_df, color=(70 / 255, 130 / 255, 180 / 255)
      )
      return plt.gcf()
  
imports: import unittest
  import pandas
  import numpy
  import pytest
  import sys
  import missingno
  import matplotlib.pyplot
label_desc: Use image node_id 5 for calling the TestMatrix obj's underlying member method code with example usage: obj.test_color_matrix() and returns: plt