git checkout exercise-05-solution
function revokeConfirmation(uint _txIndex)
public
onlyOwner
txExists(_txIndex)
notExecuted(_txIndex)
{
Transaction storage transaction = transactions[_txIndex];
require(transaction.isConfirmed[msg.sender], "tx not confirmed");
transaction.isConfirmed[msg.sender] = false;
transaction.numConfirmations -= 1;
emit RevokeConfirmation(msg.sender, _txIndex);
}