{"ast_node_type":"variable","tokens":[{"end":50,"kind":"keyword","start":0,"text":"let"}]}
        let ocx = ObligationCtxt::new(self.infcx);
    ) -> Option<(Ty<'tcx>, PredicateObligations<'tcx>)> {
        let Ok(normalized_ty) = ocx.structurally_normalize_ty(