code: def crc16(frame):
      
      crc = 0xFFFF
      for index, item in enumerate(bytearray(frame)):
          next_byte = item
          crc ^= next_byte
          for i in range(8):
              lsb = crc & 1
              crc >>= 1
              if lsb:
                  crc ^= 0xA001
      return crc
docs: Compute CRC16
  
      :param frame: frame
      :type frame: str (Python2) or class bytes (Python3)
      :returns: CRC16
      :rtype: int