> Ruby uses it in iterators (I think) and if I'm not mistaken Rust uses it with closures. Ruby and Rust both use them for closures (I assume Rust took them fro

> Ruby uses it in iterators (I think) and if I'm not mistaken Rust uses it with closures. Ruby and Rust both use them for closures (I assume Rust took them from Ruby). Nearly all of Ruby's iteration constructs are based on closures, so it makes sense that you understood them as for iterators.