ruby-base62 1.0.0-2 (amd64 binary) in ubuntu vivid

 Base62 monkeypatches Integer to add an Integer#base62_encode
 instance method to encode an integer in the character set of
 0-9 + A-Z + a-z. It also monkeypatches String to add
 String#base62_decode to take the string and turn it back
 into a valid integer.