Function with_gateway 

pub fn with_gateway<F, Fut, T>(op: F) -> Result<T>
where
    F: FnOnce(Arc<RpcIpcClient>) -> Fut,
    Fut: Future<Output = T>,

Connect to the gateway daemon and run op with a live client. The tokio runtime that hosts the muxio connection is kept alive for the whole op, so RPCs complete (dropping it early would tear down the connection and hang the call). op receives an owned Arc and runs on that runtime.