calculateStartingBalance(sortedTransactions = [], balances = []) {
    const currentBalance = balances.find(
      (balance) => 'information' === balance.balanceType.toString(),
    );

    return sortedTransactions.reduce((total, trans) => {
      return total - amountToInteger(trans.transactionAmount.amount);
    }, amountToInteger(currentBalance.balanceAmount.amount));
  }
For AMERICAN_EXPRESS_AESUDEF1 we don't know what balance was
 after each transaction so we have to calculate it by getting
 current balance from the account and subtract all the transactions

 As a current balance we use the non-standard `information` balance type
 which is the only one provided for American Express.