private async Task <ulong> GetNonceAsyncRaw(string key)
        {
            await EnsureConnected();

            IRpcClient client = this.writeClient ?? this.readClient;
            string     nonce  = await client.SendAsync <string, NonceParams>(
                "nonce",
                new NonceParams { Key = key }
                );

            return(UInt64.Parse(nonce));
        }