'Decrements a key which has a numeric value by delta. Calls incr with
-delta.
:param key: key
:param delta: amount to subtract to the value of key (or set the
value to 0 if the key is not found) will be cast to
an int
:param time: the time to live
:returns: result of decrementing
:raises MemcacheConnectionError:'

def decr(self, key, delta=1, time=0):

    return self.incr(key, delta=(- delta), time=time)
