#![allow(dead_code, deprecated, unused_variables, unused_mut)]
use std::ops::ShlAssign;
#[derive(Debug, PartialEq)]
struct Scalar(usize);
impl ShlAssign<usize> for Scalar {
    fn shl_assign(&mut self, rhs: usize) {
        self.0 <<= rhs;
    }
}
fn main() {
    let mut scalar = Scalar(4);
    scalar <<= 2;
    assert_eq!(scalar, Scalar(16));
}