syntax_data: {"ast_node_type":"other","tokens":[{"end":94,"kind":"keyword","start":0,"text":"//"}]}
source_snippet:                     // `AsyncIterator::poll_next(_, &mut Context<'_>) -> Poll<Option<Output>>`
context_before:                     // The signature should be
context_after:                     assert_eq!(sig.return_ty, tcx.types.unit);