{"ast_node_type":"other","tokens":[{"end":63,"kind":"keyword","start":0,"text":")"}]}
    ) -> (Option<ExpectedSig<'tcx>>, Option<ty::ClosureKind>) {
        predicates: impl DoubleEndedIterator<Item = (ty::Predicate<'tcx>, Span)>,
        let mut expected_sig = None;