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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 order_by_raw(self, sql, bindings=None):
 """ Add a raw "order by" clause to the query :param sql: The raw clause :type sql: str :param bindings: The bdings :param bindings: list :return: The current QueryBuilder instance :rtype: QueryBuilder """

        if bindings is None:
            bindings = []

        type = "raw"

        self.orders.append({"type": type, "sql": sql})

        self.add_binding(bindings, "order")

        return self