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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def classmarkChange(MobileStationClassmark3_presence=0):
 """CLASSMARK CHANGE Section 9.1.11"""

    a = TpPd(pd=0x6)
    b = MessageType(mesType=0x16)  # 00010110
    c = MobileStationClassmark2()
    packet = a / b / c
    if MobileStationClassmark3_presence is 1:
        e = MobileStationClassmark3(ieiMSC3=0x20)
        packet = packet / e
    return packet