That is exactly what `async` blocks are about: they do support self-referential structs, and `Pin` is what allows us to use those in a safe way, as `Pin`ned dat

That is exactly what `async` blocks are about: they do support self-referential structs, and `Pin` is what allows us to use those in a safe way, as `Pin`ned data can't be moved again (unless the data is `Unpin`, which self-referential structs are not), so the self-references are safe.