{"ast_node_type":"other","tokens":[{"end":71,"kind":"keyword","start":0,"text":"self.free_regions.row(r).into_iter().flat_map(|set|"}]}
        self.free_regions.row(r).into_iter().flat_map(|set| set.iter())
    pub(crate) fn universal_regions_outlived_by(&self, r: N) -> impl Iterator<Item = RegionVid> {
    }