syntax_data: {"ast_node_type":"variable","tokens":[{"end":66,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:             let coroutine_kind = tcx.coroutine_kind(did).unwrap();
context_before:         ty::Coroutine(did, args) => {
context_after:             let sig = args.as_coroutine().sig();