docs: def is_legal_sequence(self, packet: DataPacket) -> bool:
          """
          Check if the Sequence number of the DataPacket is legal.
          For more information see page 17 of http://tsp.esta.org/tsp/documents/docs/E1-31-2016.pdf.
          :param packet: the packet to check
          :return: true if the sequence is legal. False if the sequence number is bad
          """
          # if the sequence of the packet is smaller than the last received sequence, return false
          # therefore calculate the difference between the two values:
          try:  # try, because self.lastSequence might not been initialized
              diff = packet.sequence - self.lastSequence[packet.universe]
              # if diff is between ]-20,0], return False for a bad packet sequence
              if 0 >= diff > -20:
                  return False
          except:
              pass
          # if the sequence is good, return True and refresh the list with the new value
          self.lastSequence[packet.universe] = packet.sequence
          return True