That isn't an implementation of addition between Spans and other Spans. It looks like there isn't one in the library right now. `impl<'a> Add<Span> for &'a Zoned` means a borrow of Zoned is on the left hand side, and a Span on the right. So it says that if z is a Zoned (not a Span) and s is a Span, you can do `&z + s` to add a span to a Zoned. There are a bunch of implementations there, DateTime + Span, Date + Span, Time + Span, Offset + Span. All with Span on the right, but none for Span + Span (nor Span + &Span, or &Span + &Span, ...).
I wonder if OP will accept a PR for such a change. Your proposal is much readable and flexible (it's not clear from the docs if you can add random time ranges together). Plus, you'll be able to create your own ranges like `1.decade` or `1.application_timeframe` and add/subtract them.
mutatio|1 year ago
wging|1 year ago
csomar|1 year ago
mijoharas|1 year ago