public Yoke listen(int port, @NotNull Handler<Boolean> handler) {
        return listen(port, "0.0.0.0", handler);
    }
public Yoke listen ( int port , @ NotNull Handler < Boolean > handler ) { return listen ( port , "0.0.0.0" , handler ) ; }
Starts the server listening at a given port bind to all available interfaces.

@param port    the server TCP port
@param handler for asynchronous result of the listen operation
@return {Yoke}