public async Task <TransactionsList> GetTransactionsHistory()
 {
     try
     {
         return(await GetAsync <TransactionsList>(UrlConstants.TransactionURL()));
     }
     catch (Exception e)
     {
         return(null);
     }
 }
        public async Task <Transaction> CreateTransaction(string userName, double amount)
        {
            try
            {
                var transaction = await PostAsync <Transaction>(UrlConstants.TransactionURL(), new TransactionData { name = userName, amount = amount });

                return(transaction);
            }
            catch (Exception e)
            {
                return(null);
            }
        }