/// This will panic if `capacity` is equal to `0` or larger
/// than `usize::MAX / 2`.
#[track_caller]
pub fn channel<T: Clone>(capacity: usize) -> (Sender<T>, Receiver<T>) {
    // SAFETY: In the line below we are creating one extra receiver, so there will be 1 in total.
    let tx = unsafe { Sender::new_with_receiver_count(1, capacity) };
...
}

#[test]
    fn test(){
        broadcast::channel::<String>(usize::MAX / 2);
    }