Sets the chunk following this chunk in the list of free chunks.

        :param fwd: the chunk to follow this chunk in the list of free chunks

def set_fwd_chunk(self, fwd):
        """
        Sets the chunk following this chunk in the list of free chunks.

        :param fwd: the chunk to follow this chunk in the list of free chunks
        """
        raise NotImplementedError("%s not implemented for %s" % (self.set_fwd_chunk.__func__.__name__,
                                                                 self.__class__.__name__))