I believe this could actually not work. You would need a `fn days(n: i64) -> Span` and a `fn days(self, n: i64) -> Span` to exist at the same time, which Rust d

I believe this could actually not work. You would need a `fn days(n: i64) -> Span` and a `fn days(self, n: i64) -> Span` to exist at the same time, which Rust does not allow.