A library for handling International Standard Book Number, or ISBNs.

This library is an extension of limeburst/isbn-rs (aka isbn).

Originally it also contained patches supplied by philippeitis/isbn-rs (aka isbn2) and was topped up with a patch from CodingAnarchy/isbn-rs which set MSRV to 1.60 (which I had to bump further to 1.63 on account of indexmap). Additionally I introduced the ranges feature which isn't enabled by default, because I saw no value in the original feature for my use case.