syntax_data: {"ast_node_type":"variable","tokens":[{"end":76,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:             let coroutine_ty = Ty::new_coroutine_closure(tcx, def_id, args);
context_before:         ty::CoroutineClosure(def_id, args) => {
context_after:             let sig = args.as_coroutine_closure().coroutine_closure_sig();