use std::sync::{Arc, Mutex};

struct LockedData {
    data:i32,
}

fn main_no_release() {
    let mutex = Arc::new(Mutex::new(LockedData{data:31}));
    let guarded_data = {&mut mutex.lock().unwrap().data};
    *guarded_data += 1;
    println!("Hello, {}", mutex.lock().unwrap().data);
}

fn main() {
    let mutex = Arc::new(Mutex::new(LockedData{data:31}));
    let mut guard = mutex.lock().unwrap();
    guard.data += 1;
    std::mem::drop(guard);
    println!("Hello, {}", mutex.lock().unwrap().data);
}