public virtual async Task<MobileServiceTableOperation> GetOperationByItemIdAsync(string tableName, string itemId)
{
MobileServiceTableQueryDescription query = CreateQuery();
query.Filter = new BinaryOperatorNode(BinaryOperatorKind.And,
Compare(BinaryOperatorKind.Equal, "tableName", tableName),
Compare(BinaryOperatorKind.Equal, "itemId", itemId));
JObject op = await this.store.FirstOrDefault(query);
return MobileServiceTableOperation.Deserialize(op);
}