(1) Briefly describe how you would change your system to allow for multiple
    files to be loaded so that queries could run against more than one file
    at a time.  After all, a search engine that works for a single web page
    isn't all that useful.

(2) We required that members used as keys in a binary search tree be
    declared const.  Why?  What if all of the variants of find() returned a
    constant reference as they were originally defined in the book?  How
    would you have to change your code?