def add_arguments(self, parser):
        parser.add_argument(
            '--send-out-for-real', action='store_true', default=False,
            help='Send information to the instructors.',
        )
        parser.add_argument(
            '--no-may-contact-only', action='store_true', default=False,
            help='Include instructors not willing to be contacted.',
        )
        parser.add_argument(
            '--django-mailing', action='store_true', default=False,
            help='Use Django mailing system. This requires some environmental '
                 'variables to be set, see `settings.py`.',
        )
        parser.add_argument(
            '-s', '--sender', action='store',
            default='workshops@carpentries.org',
            help='E-mail used in "from:" field.',
        )