code: def test_required(self):
      req_flag = flag_def.SingleValueFlagDef(
          name="value",
          parse_type=str,
          required=True,
      )
  
      # Parser is able to parse a command line containing the required argument.
      results = _new_parser(req_flag).parse_args(["--value=forty-two"])
      self.assertEqual("forty-two", results.value)
  
      # Parser should raise an Exception if the commandline does not contain the
      # required argument.
      with self.assertRaisesRegex(
          argument_parser.ParserError,
          "the following arguments are required",
      ):
          _new_parser(req_flag).parse_args([])
  
imports: from __future__ import annotations
  import argparse
  import enum
  import math
  from absl.testing import absltest
  from google.generativeai.notebook import argument_parser
  from google.generativeai.notebook import flag_def
label_desc: Use image node_id 3 for calling the SingleValueFlagDefTest obj's underlying member method code with example usage: obj.test_required() without return types