code: def AddCredentialOptions(self, argument_group):
      
      argument_group.add_argument(
          '--credential', action='append', default=[], type=str,
          dest='credentials', metavar='TYPE:DATA', help=(
              'Define a credentials that can be used to unlock encrypted '
              'volumes e.g. BitLocker. The credential is defined as type:data '
              'e.g. "password:BDE-test". Supported credential types are: '
              '{0:s}. Binary key data is expected to be passed in BASE-16 '
              'encoding (hexadecimal). WARNING credentials passed via command '
              'line arguments can end up in logs, so use this option with '
              'care.').format(', '.join(self._SUPPORTED_CREDENTIAL_TYPES)))
docs: Adds the credential options to the argument group.
  
      The credential options are use to unlock encrypted volumes.
  
      Args:
        argument_group (argparse._ArgumentGroup): argparse argument group.