{"ast_node_type":"other","tokens":[{"end":79,"kind":"keyword","start":0,"text":"//"}]}
        // `fn(&mut self, args: A) -> <Self as FnOnce>::Output`, that is to say
        // because the signature of `<{async fn} as FnMut>::call_mut` is:
        // that it returns the `FnOnce`-flavored coroutine but takes the closure