code: def test_insert_field_after_index(self):
      # test insert before index and mask
      ins_aft = sa_sample.insert_field_after_index("x", 2, "$$$")
      self.assertEqual(
          "Brilliant and moving $$$ performances by "
          "Tom Courtenay and Peter Finch",
          ins_aft.get_text("x"),
      )
      self.assertEqual(ins_aft.y.field_value, "negative")
      self.assertEqual(
          [0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0], ins_aft.get_mask("x")
      )
  
file_path: textflint/test/input/component/sample/test_sa_sample.py
imports: import unittest
  from textflint.input.component.sample.sa_sample import *
label_desc: Use image node_id 2 for calling the TestSASample obj's underlying member method code with example usage: obj.test_insert_field_after_index() without return types