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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 decrby(self, key, decrement):
 """Decrement the integer value of a key by the given number. :raises TypeError: if decrement is not int """

        if not isinstance(decrement, int):
            raise TypeError("decrement must be of type int")
        return self.execute(b'DECRBY', key, decrement)