code: def setUpClass(cls):
      session._session = {
          "credentials": {},
          "config": {},
          "plot_options": {},
      }
  
file_path: plotly.py/packages/python/chart-studio/chart_studio/tests/utils.py
imports: import copy
  from unittest import TestCase
  from chart_studio import session, files, utils
  from plotly.files import ensure_writable_plotly_dir
label_desc: Use image node_id 2 for calling the PlotlyTestCase obj's underlying member method code with example usage: obj.setUpClass(cls) without return types