def __init__(self, default=False, formatter=formatter, *args, **kwargs):
        # Check that the default value is a valid filter
        if default:
            if formatter.filter_list not in default:
                raise ImproperlyConfigured("'%s' is not a registered markup filter. Registered filters are: %s." %
                                           (default, ', '.join(six.iterkeys(formatter.filter_list))))
            kwargs.setdefault('default', default)

        kwargs.setdefault('max_length', 255)
        kwargs.setdefault('choices', formatter.choices())
        kwargs.setdefault('verbose_name', ugettext_lazy('markup'))
        CharField.__init__(self, *args, **kwargs)

# Tell South how to freeze the MarkupField model.
# Because MarkupField inherits from CharField and does not add any new
# arguments, no special introspection rules are needed.
dataset/ETHPy150Open bartTC/django-markup/src/django_markup/fields.py/MarkupField.__init__/swapped operands of `not in`