{"ast_node_type":"other","tokens":[{"end":67,"kind":"keyword","start":0,"text":"(&ty::Infer(TyVar(a_id)),"}]}
            (&ty::Infer(TyVar(a_id)), &ty::Infer(TyVar(b_id))) => {
        match (a.kind(), b.kind()) {
                match self.ambient_variance {