{"ast_node_type":"other","tokens":[{"end":42,"kind":"keyword","start":0,"text":"///"}]}
    /// there exists a constraint `R: R1`.
    /// Given a region `R`, iterate over all regions `R1` such that
    pub(crate) fn outgoing_regions(&self, region_sup: RegionVid) -> Successors<'a, 'tcx, D> {