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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 _uncheck_ancestor(self, item):
 """ Uncheck the box of item and change the state of the boxes of item's ancestors accordingly. """

        self.change_state(item, "unchecked")
        parent = self.parent(item)
        if parent:
            children = self.get_children(parent)
            b = ["unchecked" in self.item(c, "tags") for c in children]
            if False in b:
                # at least one box is checked and item's box is unchecked
                self._tristate_parent(parent)
            else:
                # no box is checked
                self._uncheck_ancestor(parent)