code: def test_insert_field_after_index(self):
      # test insert before index and mask
      ins_aft = pos_sample.insert_field_after_index("x", 2, "$$$")
      self.assertEqual(
          ["That", "is", "a", "$$$", "good", "survey"],
          ins_aft.dump()["x"],
      )
      self.assertEqual(
          ins_aft.dump()["y"], ["DT", "VBZ", "DT", "UNK", "JJ", "NN"]
      )
      self.assertEqual([0, 0, 0, 2, 0, 0], ins_aft.x.mask)
      self.assertRaises(
          IndexError,
          pos_sample.insert_field_after_index,
          "x",
          10,
          "$$$",
      )
  
file_path: textflint/test/input/component/sample/test_pos_sample.py
imports: import unittest
  from textflint.input.component.sample.pos_sample import *
label_desc: Use image node_id 3 for calling the TestPOSSample obj's underlying member method code with example usage: obj.test_insert_field_after_index() without return types