code: def channelRelease(BaRange_presence=0, GroupChannelDescription_presence=0,
                     GroupCipherKeyNumber_presence=0, GprsResumption_presence=0,
                     BaListPref_presence=0):
      
      a = TpPd(pd=0x6)
      b = MessageType(mesType=0xD)  # 00001101
      c = RrCause()
      packet = a / b / c
      if BaRange_presence is 1:
          d = BaRangeHdr(ieiBR=0x73, eightBitBR=0x0)
          packet = packet / d
      if GroupChannelDescription_presence is 1:
          e = GroupChannelDescriptionHdr(ieiGCD=0x74, eightBitGCD=0x0)
          packet = packet / e
      if GroupCipherKeyNumber_presence is 1:
          f = GroupCipherKeyNumber(ieiGCKN=0x8)
          packet = packet / f
      if GprsResumption_presence is 1:
          g = GprsResumptionHdr(ieiGR=0xC, eightBitGR=0x0)
          packet = packet / g
      if BaListPref_presence is 1:
          h = BaListPrefHdr(ieiBLP=0x75, eightBitBLP=0x0)
          packet = packet / h
      return packet
docs: CHANNEL RELEASE  Section 9.1.7