code: def test_merge_by_flaglist_string(self):
      layout = go.Layout()
      layout.template = "template1+template2"
      result = layout.template
      expected = self.expected1_2
  
      self.assertEqual(result, expected)
  
      # Make sure input templates weren't modified
      self.assertEqual(self.template1, self.template1_orig)
      self.assertEqual(self.template2, self.template2_orig)
  
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 6 for calling the TestMergeTemplates obj's underlying member method code with example usage: obj.test_merge_by_flaglist_string() without return types