{"ast_node_type":"function","tokens":[{"end":91,"kind":"keyword","start":0,"text":"pub(crate)"}]}
    pub(crate) fn postdom_upper_bound(&self, fr1: RegionVid, fr2: RegionVid) -> RegionVid {
    /// the postdominating upper bound in general.)
        assert!(self.universal_regions.is_universal_region(fr1));