function executeTransaction(uint transactionId)
        public
        notExecuted(transactionId)
    {
        if (isConfirmed(transactionId)) {
            Transaction mtx = transactions[transactionId];
            mtx.executed = true;
            if (mtx.destination.call.value(mtx.value)(mtx.data))
                Execution(transactionId);
            else {
                ExecutionFailure(transactionId);
                mtx.executed = false;
            }
        }
    }