docs: def _calculate_checksum(value):
          """4.12 Checksum Calculation from an unsigned short input"""
          # CRC
          polynomial = 0x131  # //P(x)=x^8+x^5+x^4+1 = 100110001
          crc = 0xFF
  
          # calculates 8-Bit checksum with given polynomial
          for byteCtr in [ord(x) for x in struct.pack(">H", value)]:
              crc ^= byteCtr
              for bit in range(8, 0, -1):
                  if crc & 0x80:
                      crc = (crc << 1) ^ polynomial
                  else:
                      crc = (crc << 1)
          return crc