isbn ==== Version 2.0 This library provides methods to manipulate isbns. As of version 2.0 there has been a near complete rewrite of this library but this time there are tests. A few methods have been removed. Here is what remains: * ISBN.ten will return a 10 digit isbn if you give it a 10 or 13 digit isbn - it will raise a No10DigitISBNAvailable error if given an isbn starting with 979 because 979 isbns do NOT have a 10 digit counterpart. * ISBN.thirteen will return a 13 digit isbn if you give it 10 or thirteen digit isbn * ISBN.as_new will convert an isbn into the used book version for that isbn - for isbns starting with 978 it returns an isbn starting with 290 - for isbns starting with 979 it returns an isbn starting with 291 * ISBN.as_used will convert an isbn into the new book version for that isbn - for isbns starting with 290 it returns an isbn starting with 978 - for isbns starting with 291 it returns an isbn starting with 979 * ISBN.valid? will compare the check digit of the passed in isbn with that of one it computes * ISBN.from_image accept a jpeg of an isbn and OCR it into an isbn. - it depends on the LibJpeg and Gocr libraries. I recommend [Homebrew](http://github.com/mxcl/homebrew). * ISBN.from_string fetches isbn from string