Function launch_cfx_async_rpc_servers 

pub async fn launch_cfx_async_rpc_servers(
    consensus: SharedConsensusGraph,
    sync: SharedSynchronizationService,
    tx_pool: SharedTransactionPool,
    data_man: Arc<BlockDataManager>,
    network: Arc<NetworkService>,
    pos_handler: Arc<PosVerifier>,
    notifications: Arc<Notifications>,
    executor: TaskExecutor,
    accounts: Arc<AccountProvider>,
    exit: Arc<(Mutex<bool>, Condvar)>,
    block_gen: BlockGeneratorTestApi,
    maybe_txgen: Option<Arc<TransactionGenerator>>,
    maybe_direct_txgen: Option<Arc<Mutex<DirectTransactionGenerator>>>,
    conf: &Configuration,
    apis: ApiSet,
    is_debug: bool,
) -> Result<Option<RpcServerHandle>, String>