syntax_data: {"ast_node_type":"other","tokens":[{"end":68,"kind":"keyword","start":0,"text":"//"}]}
source_snippet:                         // implementations return `FnOnce::Output`).
context_before:                         // sync with the built-in trait implementations (since all of the
context_after:                         if ty::ClosureKind::FnOnce == args.as_coroutine_closure().kind() {