Function lancat::listen

pub fn listen<W, C>(
    discovery_addr: &SocketAddrV4, 
    users: Option<&Vec<String>>, 
    user_name: &str, 
    service_addr: &SocketAddr, 
    once: bool, 
    callback: C, 
    output: W
) where
    C: FnMut(&str, &SocketAddr) + Send + Sync,
    W: Write + Send,