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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 cas(self, key, value, cas, time=0, compress_level=-1):
 """ Set a value for a key on server if its CAS value matches cas. :param key: Key's name :type key: six.string_types :param value: A value to be stored on server. :type value: object :param cas: The CAS value previously obtained from a call to get*. :type cas: int :param time: Time in seconds that your key will expire. :type time: int :param compress_level: How much to compress. 0 = no compression, 1 = fastest, 9 = slowest but best, -1 = default compression level. :type compress_level: int :return: True in case of success and False in case of failure :rtype: bool """

        server = self._get_server(key)
        return server.cas(key, value, cas, time, compress_level)