def last_child_position(self, pos):
        candidate = None
        subtree = self._get_subtree(self._treelist, pos)
        if subtree is not None:
            children = subtree[1]
            if children is not None:
                candidate = pos + (1 - len(children),)
        return candidate
dataset/ETHPy150Open kdart/pycopia/QA/pycopia/QA/tui/walkers.py/SimpleTreeWalker.last_child_position/swapped operands of `-`