syntax_data: {"ast_node_type":"variable","tokens":[{"end":60,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:             let (resume_ty, ret_ty) = match coroutine_kind {
context_before:             // special coroutine backing a gen construct.
context_after:                 hir::CoroutineKind::Desugared(hir::CoroutineDesugaring::Async, _) => {