You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: forktest2.rs
    path of file: ./repos/os_kernel_lab/user/src/bin
    
    the code of the file until where you have to start completion: #![no_std]
#![no_main]

#[macro_use]
extern crate user_lib;

use user_lib::{exit, fork, get_time, getpid, sleep, wait};

static NUM: usize = 30;

#[no_mangle]
pub fn main() -> i32 {
    for _ in 0..NUM {
        let pid = fork();
        if pid == 0 {
            let current_time = get_time();
            let sleep_length =
                (current_time as i32 as isize) * (current_time as i32 as isize) % 1000 + 1000;
            println!("pid {} sleep for
    
pub fn main() -> i32 {
    for _ in 0..NUM {
        let pid = fork();
        if pid == 0 {
            let current_time = get_time();
            let sleep_length =
                (current_time as i32 as isize) * (current_time as i32 as isize) % 1000 + 1000;
            println!("pid {} sleep for {} ms", getpid(), sleep_length);
            sleep(sleep_length as usize);
            println!("pid {} OK!", getpid());
            exit(0);
        }
    }

    let mut exit_code: i32 = 0;
    for _ in 0..NUM {
        assert!(wait(&mut exit_code) > 0);
        assert_eq!(exit_code, 0);
    }
    assert!(wait(&mut exit_code) < 0);
    println!("forktest2 test passed!");
    0
}