Demonstrate a method of deriving the [[wp:Computation of cyclic redundancy checks|Cyclic Redundancy Check]] from within the language.
The result should be in accordance with ISO 3309, [http://www.itu.int/rec/T-REC-V.42-200203-I/en ITU-T V.42], [http://tools.ietf.org/html/rfc1952 Gzip] and [http://www.w3.org/TR/2003/REC-PNG-20031110/ PNG].
Algorithms are described on [[wp:Cyclic redundancy check|Computation of CRC]] in Wikipedia.