{"ast_node_type":"other","tokens":[{"end":47,"kind":"keyword","start":0,"text":"infcx.enter_forall(a,"}]}
                    infcx.enter_forall(a, |a| {
                    // Check if `exists<..> B == for<..> A`.
                        let b = infcx.instantiate_binder_with_fresh_vars(span, HigherRankedType, b);