@classmethod
def sort(cls, *columns):
    """
        Shortcut for smart_query() method
        Example 1:
            User.sort('first_name','-user_id')
        This is equal to
            db.query(User).order_by(*User.order_expr('first_name','-user_id'))

        Example 2:
            columns = ['first_name','-user_id']
            User.sort(*columns)
        This is equal to
            columns = ['first_name','-user_id']
            db.query(User).order_by(*User.order_expr(*columns))

        Exanple 3 (with joins):
            Post.sort('comments___rating', 'user___name').all()
        """
    return cls.smart_query({}, columns)
