syntax_data: {"ast_node_type":"other","tokens":[{"end":90,"kind":"keyword","start":0,"text":"if"}]}
source_snippet:                         if ty::ClosureKind::FnOnce == args.as_coroutine_closure().kind() {
context_before:                         // implementations return `FnOnce::Output`).
context_after:                             Some(Instance::new_raw(coroutine_closure_def_id, args))