{"ast_node_type":"other","tokens":[{"end":75,"kind":"keyword","start":0,"text":"debug!(\"make_eqregion:"}]}
                    debug!("make_eqregion: unifying {:?} with {:?}", a, b);
                (ty::ReVar(a), ty::ReVar(b)) => {
                    if self.unification_table_mut().unify_var_var(a, b).is_ok() {