Catalog Requests: Authenticated vs Unauthenticated.

[Mbucari]

As you know, you may make unauthenticated requests to the catalog endpoint to receive product information. Making an authenticated request returns nearly identical data with one important difference: products that are unavailable to the account holder will not have a "price" array when making an authenticated request.

This has been useful in making a series viewer in Libation. If you query all the series children for a given parent, many of those children will be duplicate of the same book from different publishers, and only some of those duplicates are available for purchase by the user. By making an authenticated request you can distinguish unavailable books from available books by the absence/presence of a price.