use std::future::Future;

trait Handler {}

struct W<T>(T);

trait SendTarget {
    fn call(self) -> impl Future<Output = ()> + Send;
}

impl<T> SendTarget for W<T>
where
    T: Handler + Send,
{
    async fn call(self) {
        todo!()
    }
}

impl<T> SendTarget for T
where
    T: Handler + Send,
{
    async fn call(self) {
        W(self).call().await
    }
}

fn main() {}