fn get_new_message_handler(channel: Mutex<mpsc::Sender<Update>>) -> impl Fn((&EventApi, &UpdateNewMessage)) -> TGResult<()> + 'static {
    move|(api, update)| {
        let local = channel.lock().unwrap();
        local.send(Update::NewMessage(update.clone())).unwrap();
        Ok(())
    }
}

pub fn on_update_new_message<F>(&mut self, fnc: F) -> &mut Self
       where F: Fn((&EventApi, &UpdateNewMessage)) -> TGResult<()> + Send + Sync + 'static

...

listener.on_update_new_message(get_new_message_handler(channel));