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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def add_argument(self, parser, permissive=False, **override_kwargs):
 """Add an option to a an argparse parser. :keyword permissive: when true, build a parser that does not validate required arguments. """

        kwargs = {}
        required = None
        if self.kwargs:
            kwargs = copy.copy(self.kwargs)
            if 'env' in kwargs and 'help' in kwargs:
                kwargs['help'] = "%s (or set %s)" % (kwargs['help'],
                                                     kwargs['env'])
            if permissive:
                required = kwargs.pop('required', None)
            try:
                del kwargs['env']
            except KeyError:
                pass
            try:
                del kwargs['ini_section']
            except KeyError:
                pass

            # allow custom and/or exclusive argument groups
            if kwargs.get('group') or kwargs.get('mutually_exclusive'):
                groupname = kwargs.pop('group', None) or kwargs.get('dest')
                mutually_exclusive = kwargs.pop('mutually_exclusive', None)
                if not groupname:
                    raise NoGroupForOption(
                        "%s requires either 'group' or 'dest'." % self)
                description = kwargs.pop('group_description', None)
                exists = [grp for grp in parser._action_groups
                          if grp.title == groupname]
                if exists:
                    group = exists[0]
                    if description and not group.description:
                        group.description = description
                else:
                    group = parser.add_argument_group(
                        title=groupname, description=description)
                if mutually_exclusive:
                    if not required:
                        required = kwargs.pop('required', None)
                    mutexg_title = '%s mutually-exclusive-group' % groupname
                    exists = [grp for grp in group._mutually_exclusive_groups
                              if grp.title == mutexg_title]
                    if exists:
                        group = exists[0]
                    else:
                        # extend parent group
                        group = group.add_mutually_exclusive_group(
                            required=required)
                        group.title = mutexg_title
                    # if any in the same group are required, then the
                    # mutually exclusive group should be set to required
                    if required and not group.required:
                        group.required = required
                    self._mutexgroup = group
                self._action = group.add_argument(*self.args, **kwargs)
                return

        kwargs.update(override_kwargs)
        self._action = parser.add_argument(*self.args, **kwargs)