Function gib 

pub const fn gib(n: usize) -> usize

Multiply by 1024³ to express a byte count in gibibytes (GiB).

Returns usize; use gib_u64 when you need a u64.

use rama_utils::octets::gib;
const LIMIT: usize = gib(2);
assert_eq!(LIMIT, 2 * 1024 * 1024 * 1024);