The WWW::Scraper::ISBN class was built as a way to retrieve information on
books from multiple sources easily. It utilizes at least one driver
implemented as a subclass of WWW::Scraper::ISBN::Driver, each of which is
designed to scrape from a single source. Because we found that different
sources had different information available on different books, we designed
a basic interface that could be implemented in whatever ways necessary to
retrieve the desired information.