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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 decr(self, key, value, default=0, time=100):
 """ Decrement a key, if it exists, returns its actual value, if it doesn't, return 0. Minimum value of decrement return is 0. :param key: Key's name :type key: six.string_types :param value: Number to be decremented :type value: int :param default: Default value if key does not exist. :type default: int :param time: Time in seconds to expire key. :type time: int :return: Actual value of the key on server :rtype: int """

        return self._incr_decr('decr', key, value, default, time)