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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 unselect_all(self):
 """ Clearing the selected_item also clears the focused_item. """

        items = self._get_selected_items()
        with self._suppress_selection_events():
            self._selection.clear()
        self.queue_draw_item(*items)
        self.emit('selection-changed', self._get_selected_items())