This module calculates the Modulus 10 Double Add Double checksum,
also known as the LUHN Formula. This algorithm is used to verify
credit card numbers and Standard & Poor's security identifiers such
as CUSIP's and CSIN's.

You can find plenty of information about the algorithm by searching
the web for "modulus 10 double add double".

Homepage:
https://metacpan.org/pod/Algorithm::LUHN
