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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 addend_idxs(self):
 """tuple of int index of each addend element for this subtotal. The length of the tuple is the same as that for `.addend_ids`, but each value repesents the offset of that element within the dimension, rather than its element id. """

        return tuple(
            self.valid_elements.get_by_id(addend_id).index_in_valids
            for addend_id in self.addend_ids
        )