Stage 5.4: Option

Rust has a built-in generic enum called Option<T> that allows us to represent nullable values without using null.

Option<T> has the 2 values None and Some(T)

This enum is so common, instances of the enum can be created anywhere with the enum variants Some and None.

Further information:

• https://doc.rust-lang.org/std/option/enum.Option.html
• https://doc.rust-lang.org/rust-by-example/std/option.html