use async_trait::async_trait;
use std::time::{Duration, Instant};
#[async_trait]
pub trait Clock: Send + Sync {
    fn now(&self) -> Instant;
    async fn sleep(&self, duration: Duration);
}
pub struct SystemClock;
#[async_trait]
impl Clock for SystemClock {
    fn now(&self) -> Instant {
        Instant::now()
    }
    async fn sleep(&self, duration: Duration) {
        tokio::time::sleep(duration).await;
    }
}