$ crc32.py -h
usage: crc32.py [-h] action ...

Reverse, undo, and calculate CRC32 checksums

positional arguments:
  action
    poly (p)   print the polynomial, useful for converting between forms
    table (t)  generate a lookup table for a polynomial
    reverse (r)
               find a patch that causes the CRC32 checksum to become a desired value
    undo (u)   rewind a CRC32 checksum
    calc (c)   calculate the CRC32 checksum

options:
  -h, --help   show this help message and exit