fails:Zlib.crc32 calculates CRC checksum for string
fails:Zlib.crc32 calculates CRC checksum for string and initial CRC value
fails:Zlib.crc32 calculates the CRC checksum for string and initial CRC value for Bignums
fails:Zlib.crc32 assumes that the initial value is given to crc, if crc is omitted
fails:Zlib.crc32 it returns the CRC initial value, if string is omitted
