Function into_handler 

pub fn into_handler<F, Fut>(f: F) -> MessageHandler
where
    F: Fn(Message) -> Fut + Send + Sync + 'static,
    Fut: Future<Output = Result<Option<String>>> + Send + 'static,

Wrap a generic async closure into a MessageHandler.

Example

use chat_system::server::into_handler;

let h = into_handler(|msg| async move {
    println!("got: {}", msg.content);
    Ok(Some("thanks!".into()))
});