syntax_data: {"ast_node_type":"other","tokens":[{"end":88,"kind":"keyword","start":0,"text":"//!"}]}
source_snippet: //! `FnOnce`/`AsyncFnOnce` implementations for coroutine-closures (e.g. async closures).
context_before: //! This pass constructs a second coroutine body sufficient for return from
context_after: //!