Threads in rust

  use std::fs::OpenOptions;
  use std::io::Write;
  use std::time::SystemTime;

  fn write(path: String) -> Result<(), std::io::Error> {
      let mut file = OpenOptions::new()
          .create(true)
          .write(true)
          .append(true)
          .open(path)?;

      loop {
          let now = SystemTime::now();
          let datetime = chrono::DateTime::<chrono::Local>::from(now);

          let time_now = datetime.to_string();

          if let Err(e) = writeln!(file, "{}", time_now) {
              eprintln!("Couldn't write to file: {}", e);
          }

          if let Err(e) = file.flush() {
              eprintln!("Couldn't flush buffer: {}", e);
          }

          std::thread::sleep(std::time::Duration::from_millis(1000));
      }
  }

  fn main() -> Result<(), std::io::Error> {
      std::thread::spawn(|| write("/tmp/a.txt".to_string()).unwrap());
      std::thread::spawn(|| write("/tmp/b.txt".to_string()).unwrap());
      std::io::stdin().read_line(&mut String::new()).map(std::mem::drop)
  }