code: def test_update(self):
      fig, ax = plt.subplots()
      ax.plot([1, 2, 3])
      title = "new title"
      update = {"layout": {"title": title}}
      url = py.plot_mpl(
          fig, update=update, filename="nosetests", auto_open=False
      )
      un = url.replace("https://plotly.com/~", "").split("/")[0]
      fid = url.replace("https://plotly.com/~", "").split("/")[1]
      pfig = py.get_figure(un, fid)
      assert pfig["layout"]["title"]["text"] == title
  
file_path: plotly.py/packages/python/chart-studio/chart_studio/tests/test_optional/test_matplotlylib/test_plot_mpl.py
imports: from __future__ import absolute_import
  import _plotly_utils.exceptions
  from plotly import optional_imports
  from chart_studio.plotly import plotly
  from unittest import TestCase
  import pytest
label_desc: Use image node_id 4 for calling the PlotMPLTest obj's underlying member method code with example usage: obj.test_update() without return types