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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 additionalAssignment(MobileAllocation_presence=0, StartingTime_presence=0):
 """ADDITIONAL ASSIGNMENT Section 9.1.1"""

    # Mandatory
    a = TpPd(pd=0x6)
    b = MessageType(mesType=0x3B)  # 00111011
    c = ChannelDescription()
    packet = a / b / c
    # Not Mandatory
    if MobileAllocation_presence is 1:
        d = MobileAllocationHdr(ieiMA=0x72, eightBitMA=0x0)
        packet = packet / d
    if StartingTime_presence is 1:
        e = StartingTimeHdr(ieiST=0x7C, eightBitST=0x0)
        packet = packet / e
    return packet