syntax_data: {"ast_node_type":"other","tokens":[{"end":25,"kind":"keyword","start":0,"text":"{"}]}
source_snippet:                         {
context_before:                             && args.as_coroutine_closure().kind() != ClosureKind::FnOnce
context_after:                             // If we're computing `AsyncFnOnce` for a by-ref closure then