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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 query(self, expr):
 """ Query the data with a boolean expression. :param expr: the query string, you can use '@' character refer to environment variables. :return: new collection :rtype: :class:`odps.df.expr.expressions.CollectionExpr` """

        from .query import CollectionVisitor

        if not isinstance(expr, six.string_types):
            raise ValueError('expr must be a string')

        frame = sys._getframe(2).f_locals
        try:
            env = frame.copy()
        finally:
            del frame

        visitor = CollectionVisitor(self, env)
        predicate = visitor.eval(expr)
        return self.filter(predicate)