def METHOD_NAME(self, days, field='pub_date'):
    """
    Filter organizations by creation date.
    :param days: Days ago that organization was created
    :param field: Field name to use in comparison, default: pub_date
    """
    when = timezone.now() - timedelta(days=days)
    query_filter = {}
    query_filter[field + '__year'] = when.year
    query_filter[field + '__month'] = when.month
    query_filter[field + '__day'] = when.day
    return self.filter(**query_filter)