syntax_data: {"ast_node_type":"other","tokens":[{"end":77,"kind":"keyword","start":0,"text":"//!"}]}
source_snippet: //! since all async closures implement that too)? Well, recall the signature:
context_before: //! However, what happens when we call `closure` with `AsyncFnOnce` (or `FnOnce`,
context_after: //! ```