2 implement lookup 3

OK, here's a new branch with a total of 8 commits.

All of the original commits (development history, warts, etc.) are still available on 2_implement_lookup_2.

We can continue to iterate on this process until we finally have a nice "story-telling" set of commits that make it easy for someone following the development of the code-base to learn how things were built.

Or maybe this branch will be good enough.   At any rate, we've got the complete (true) history, and a revised version that makes for easier reading to merge into production.

Looking forward to your review comments, and further iterations of improvement.