code: def test_insert_field_after_index(self):
      # test insert before index and mask
      ins_aft = nli_sample.insert_field_after_index(
          "hypothesis", 2, "$$$"
      )
      self.assertEqual(
          "MR zhang has $$$ 10 students", ins_aft.get_text("hypothesis")
      )
      self.assertEqual(ins_aft.y.field_value, "contradiction")
      self.assertEqual(
          [0, 0, 0, 2, 0, 0], ins_aft.get_mask("hypothesis")
      )
  
file_path: textflint/test/input/component/sample/test_nli_sample.py
imports: import unittest
  from textflint.input.component.sample.nli_sample import *
label_desc: Use image node_id 2 for calling the TestNLISample obj's underlying member method code with example usage: obj.test_insert_field_after_index() without return types