Look in sub-diurecotries for original book content that has been deprecated. The old book chapter is now a README.md file. For example, I deprecated the Zapier example so that book chapter is now available at https://github.com/mark-watson/langchain-book-examples/blob/main/CHAPTERS_and_CODE_no_longer_in-book/zapier_integrations/README.md and the original Python code examples are in the same directory as the book chapter.