Class _ArgumentGroup

Lib/argparse.py:1831–1873

class _ArgumentGroup(_ActionsContainer):

    def __init__(self, container, title=None, description=None, **kwargs):
        if 'prefix_chars' in kwargs:
            import warnings
            depr_msg = (
                "The use of the undocumented 'prefix_chars' parameter in "
                "ArgumentParser.add_argument_group() is deprecated."
            )
            warnings.warn(depr_msg, DeprecationWarning, stacklevel=3)

        # add any missing keyword arguments by checking the container
        update = kwargs.setdefault
        update('conflict_handler', container.conflict_handler)
        update('prefix_chars', container.prefix_chars)
        update('argument_default', container.argument_default)
        super_init = super(_ArgumentGroup, self).__init__
        super_init(description=description, **kwargs)

        # group attributes
        self.title = title
        self._group_actions = []

        # share most attributes with the container
        self._registries = container._registries
        self._actions = container._actions
        self._option_string_actions = container._option_string_actions
        self._defaults = container._defaults
        self._has_negative_number_optionals = \
            container._has_negative_number_optionals
        self._mutually_exclusive_groups = container._mutually_exclusive_groups

    def _add_action(self, action):
        action = super(_ArgumentGroup, self)._add_action(action)
        self._group_actions.append(action)
        return action

    def _remove_action(self, action):
        super(_ArgumentGroup, self)._remove_action(action)
        self._group_actions.remove(action)

    def add_argument_group(self, *args, **kwargs):
        raise ValueError('argument groups cannot be nested')

class _MutuallyExclusiveGroup(_ArgumentGroup):