docs: def init_argparser_optional_advice(
              self, argparser, default=[], help=(
                  'a comma separated list of packages to retrieve optional '
                  'advice from; the provided packages should have registered '
                  'the appropriate entry points for setting up the advices for '
                  'the toolchain; refer to documentation for the specified '
                  'packages for details'
              )):
          """
          For setting up optional advice.
          """
  
          argparser.add_argument(
              '--optional-advice', default=default, required=False,
              dest=ADVICE_PACKAGES, action=StoreRequirementList,
              metavar='<advice>[,<advice>[...]]',
              help=help
          )