def _mask_crc(crc):
  """Mask crc.

  Args:
    crc: integer crc.
  Returns:
    masked integer crc.
  """
  return (((crc >> 15) | (crc << 17)) - _CRC_MASK_DELTA) & 0xFFFFFFFFL
dataset/ETHPy150Open AppScale/appscale/AppServer/google/appengine/api/files/records.py/_mask_crc/operator `+` -> `-`