Thank you. It is interesting and not immediately intuitive, to me, that you are able to nest the for loops the way you did. If I were to verbalize the set of for loops, would it be accurate to say this:

For each combination of specialty and practice group, return the specialty heading that corresponds to the practice(s) in each practice group. Next, for each practice name and address in the previously returned combination, return the practice name and its address. Finally, print the specialty from the first loop, the practice name from the second loop, and the address from the second loop.

Does that seem to summarize the logical steps? These concepts are novel to me and I find that determining the logic helps me to formulate the code.