protected async Task <IMutateOperationResult> PerformMutate(MutationMode mode, string key, Expiration expiration, ulong delta, ulong defaultValue, ulong cas) { try { var op = opFactory.Mutate(mode, keyTransformer.Transform(key), expiration.Value, delta, defaultValue, cas); await cluster.Execute(op).ConfigureAwait(false); return(op.Result); } catch (IOException e) { return(new MutateOperationResult().FailWith(e)); } }