#![allow(dead_code, deprecated, unused_variables, unused_mut)]
use std::any::Any;
fn modify_if_u32(s: &mut (dyn Any + Send + Sync)) {
    if let Some(num) = s.downcast_mut::<u32>() {
        *num = 42;
    }
}
fn main() {
    let mut x = 10u32;
    let mut s = "starlord".to_string();
    modify_if_u32(&mut x);
    modify_if_u32(&mut s);
    assert_eq!(x, 42);
    assert_eq!(& s, "starlord");
}