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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 set_bck_chunk(self, bck):
 """ Sets the chunk backward from this chunk in the list of free chunks. :param bck: the chunk to precede this chunk in the list of free chunks """

        raise NotImplementedError("%s not implemented for %s" % (self.set_bck_chunk.__func__.__name__,
                                                                 self.__class__.__name__))