code: def test_insert_after_index(self):
      test_field = CnTextField(sents[0])
      self.assertRaises(
          AssertionError, test_field.insert_after_index, 5, ""
      )
  
      self.assertEqual(
          "我们正在好的玩乒乓球，你真的太懒了。她打的很漂亮。",
          test_field.insert_after_index(3, "好的").text,
      )
      self.assertEqual(
          "我们正在好的玩乒乓球，你真的太懒了。她打的很漂亮。",
          test_field.insert_after_index(3, ["好的"]).text,
      )
      self.assertEqual(
          "我们正在好的玩乒乓球，你真的太懒了。她打的很漂亮。",
          test_field.insert_after_index(3, ["好", "的"]).text,
      )
  
imports: import unittest
  from textflint.input.component.field.cn_text_field import *
label_desc: Use image node_id 9 for calling the TestCnTextField obj's underlying member method code with example usage: obj.test_insert_after_index() without return types