What new features would you add to programming languages?

I’m jealous of Haskell’s ‘where bindings’ [1], even if only to push what in (say) Python would be an assignment to below its use, so that more important things come first. You could have multi-line functions that look like ‘return...where:’ and I’d love that.

[1] https://wiki.haskell.org/Let_vs._Where