Macro i256 

macro_rules! i256 {
    ($($body:tt)*) => { ... };
}

A macro to construct 256-bit I256 signed integer from literals.

Examples:

use fastnum::{i256, I256};

const N: I256 = i256!(100);
let x = i256!(1);
assert!(i256!(0).is_zero());
println!("{x}");