[csande17]

Rust has a feature called "tuple structs" where the properties of the struct are accessed by numeric indices instead of names: https://doc.rust-lang.org/book/ch05-01-defining-structs.html... / https://doc.rust-lang.org/book/ch05-02-example-structs.html#...

In most other languages this would be written as "this.current_index" or some other property name.