{"ast_node_type":"variable","tokens":[{"end":73,"kind":"keyword","start":0,"text":"let"}]}
        let OpaqueTypeStorage { opaque_types, duplicate_entries } = self;
    ) -> impl Iterator<Item = (OpaqueTypeKey<'tcx>, OpaqueHiddenType<'tcx>)> {
        opaque_types.iter().map(|(k, v)| (*k, *v)).chain(duplicate_entries.iter().copied())