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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 select_raw(self, expression, bindings=None):
 """ Add a new raw select expression to the query :param expression: The raw expression :type expression: str :param bindings: The expression bindings :type bindings: list :return: The current QueryBuilder instance :rtype: QueryBuilder """

        self.add_select(QueryExpression(expression))

        if bindings:
            self.add_binding(bindings, "select")

        return self