zendesk/credit_card_sanitizer — pull request #1 by andreionut (2014-07-08 12:49:52+00:00)
Title: Check if the size of the number found is between 13 and 19.

This is the PAN length range for major card schemes.

See https://en.wikipedia.org/wiki/Primary_Account_Number#Issuer_identification_number_.28IIN.29