Public Sub RollbackTransaction( _
   ByRef token As TransactionToken _
) 

public void RollbackTransaction( 
   ref TransactionToken token
)

using (TempFile tmp = new TempFile())
using (var log = new TransactionLog<int, string>(Options(tmp)))
{
    var token = log.BeginTransaction();
    log.AddValue(ref token, 1, "test");
    log.RollbackTransaction(ref token);

    var test = new Dictionary<int, string>();
    log.ReplayLog(test);
    Assert.AreEqual(0, test.Count);
}

Using tmp As New TempFile()
    Using log As var = New TransactionLog(Of Integer, String)(Options(tmp))
        Dim token As var = log.BeginTransaction()
        log.AddValue(token, 1, "test")
        log.RollbackTransaction(token)

        Dim test As var = New Dictionary(Of Integer, String)()
        log.ReplayLog(test)
        Assert.AreEqual(0, test.Count)
    End Using
End Using