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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 reduce_slice(self, start, end, options=None):
 """ Adds the Javascript built-in ``Riak.reduceSlice`` to the query as a reduce phase. :param start: the beginning of the slice :type start: integer :param end: the end of the slice :type end: integer :param options: phase options, containing 'language', 'keep' flag, and/or 'arg'. :type options: dict """

        if options is None:
            options = dict()

        options['arg'] = [start, end]
        return self.reduce("Riak.reduceSlice", options=options)