{"ast_node_type":"function","tokens":[{"end":84,"kind":"keyword","start":0,"text":"pub(crate)"}]}
    pub(crate) fn non_local_lower_bound(&self, fr: RegionVid) -> Option<RegionVid> {
    /// one. See `TransitiveRelation::postdom_upper_bound` for details.
        debug!("non_local_lower_bound(fr={:?})", fr);