{"ast_node_type":"other","tokens":[{"end":59,"kind":"keyword","start":0,"text":"pub(crate)"}]}
pub(crate) trait ConstraintGraphDirection: Copy + 'static {
/// represents an edge `R1 -> R2` or `R2 -> R1`.
    fn start_region(sup: RegionVid, sub: RegionVid) -> RegionVid;