code: def test_update_template_with_flaglist(self):
      fig = go.Figure()
      fig.update(layout_template="template1+template2")
      result = fig.layout.template
      expected = self.expected1_2
      self.assertEqual(result, expected)
  
imports: import copy
  from unittest import TestCase
  import pytest
  import plotly.io
  import plotly.graph_objs
  from plotly.tests.utils import TestCaseNoTemplate
label_desc: Use image node_id 8 for calling the TestMergeTemplates obj's underlying member method code with example usage: obj.test_update_template_with_flaglist() without return types