code: def detachRequest(GmmCause_presence=0):
      
      a = TpPd(pd=0x3)
      b = MessageType(mesType=0x5)  # 00000101
      c = DetachTypeAndForceToStandby()
      packet = a / b / c
      if GmmCause_presence is 1:
          e = GmmCause(ieiGC=0x25)
          packet = packet / e
      return packet
docs: DETACH REQUEST Section 9.4.5