[runiq]

If you think of it as 'a implements b', it makes sense for both lifetimes and (other) subtypes: If lifetime `a` implements `b`, it is obviously valid for `b` (and maybe longer).

[LoganDark]

I always do `<T, U extends T, V extends U>` etc for generics, but for lifetimes it's `<'a: 'b, 'b: 'c, 'c>` which always trips me up...