{"ast_node_type":"other","tokens":[{"end":54,"kind":"keyword","start":0,"text":"hir::CoroutineDesugaring::Gen"}]}
                    hir::CoroutineDesugaring::Gen => {
                let (bound_return_ty, bound_yield_ty) = match kind {
                        // `iter!` closures always return unit and yield the `Iterator::Item` type