Chapter 12 code error

[brisksea]

def createInitSet(dataSet):
    retDict = {}
    for trans in dataSet:
        retDict[frozenset(trans)] = 1
    return retDict

the code retDict[frozenset(trans)] = 1, not consider when two transactions are the same.
should changed to

def createInitSet(dataSet):
    retDict = {}
    for trans in dataSet:
        retDict[frozenset(trans)] = retDict.get(frozenset(trans), 0) + 1
    return retDict