docs: def inv_endianness(pkt):
          """ Invert the order of the first four bytes of a CAN packet
  
          This method is meant to be used specifically to convert a CAN packet
          between the pcap format and the socketCAN format
  
          :param pkt: str of the CAN packet
          :return: packet str with the first four bytes swapped
          """
          len_partial = len(pkt) - 4  # len of the packet, CAN ID excluded
          return struct.pack('<I{}s'.format(len_partial),
                             *struct.unpack('>I{}s'.format(len_partial), pkt))