code: def test_delete_field_at_index(self):
      # test delete at index
      delete = mrc_sample.delete_field_at_index("context", 2)
      self.assertTrue(delete.is_legal())
      self.assertEqual(
          "Super Bowl was an American football game to "
          "determine the champion "
          "of the National Football League (NFL) for the 2015 season.",
          delete.get_sentences("context")[0],
      )
  
file_path: textflint/test/input/component/sample/test_mrc_sample.py
imports: import unittest
  from textflint.input.component.sample.mrc_sample import MRCSample
label_desc: Use image node_id 5 for calling the TestMRCSample obj's underlying member method code with example usage: obj.test_delete_field_at_index() without return types