code: def crc16_nojit(s, crc=0):
    
    for ch in bytearray(s):  # bytearray's elements are integers in both python 2 and 3
      crc = ((crc << 8) & 0xFFFF) ^ _crc16_tab[((crc >> 8) & 0xFF) ^ (ch & 0xFF)]
      crc &= 0xFFFF
    return crc
docs: CRC16 implementation acording to CCITT standards.