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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 incr(self, key, incr_by=1.):
 """ Increment the score of an item in the ZSet. :param key: Item to increment. :param incr_by: Amount to increment item's score. """

        return self.database.zincrby(self.key, incr_by, key)