#![allow(dead_code, deprecated, unused_variables, unused_mut)]
use std::ops::Neg;
#[derive(Debug, PartialEq)]
enum Sign {
    Negative,
    Zero,
    Positive,
}
impl Neg for Sign {
    type Output = Self;
    fn neg(self) -> Self::Output {
        match self {
            Sign::Negative => Sign::Positive,
            Sign::Zero => Sign::Zero,
            Sign::Positive => Sign::Negative,
        }
    }
}
fn main() {
    assert_eq!(- Sign::Positive, Sign::Negative);
    assert_eq!(- Sign::Negative, Sign::Positive);
    assert_eq!(- Sign::Zero, Sign::Zero);
}