code: def DEFINE_boolean(flag_name, default_value, docstring):  # pylint: disable=invalid-name
      
  
      # Register a custom function for 'bool' so --flag=True works.
      def str2bool(bool_str):
          """Return a boolean value from a give string."""
          return bool_str.lower() in ('true', 't', '1')
  
      get_context_parser().add_argument(
          '--' + flag_name,
          nargs='?',
          const=True,
          help=docstring,
          default=default_value,
          type=str2bool)
  
      # Add negated version, stay consistent with argparse with regard to
      # dashes in flag names.
      get_context_parser().add_argument(
          '--no' + flag_name,
          action='store_false',
          dest=flag_name.replace('-', '_'))
docs: Defines a flag of type 'boolean'.
      Args:
          flag_name: The name of the flag as a string.
          default_value: The default value the flag should take as a boolean.
          docstring: A helpful message explaining the use of the flag.