I need to add a single integer to a list that's already sorted, such
that it goes in the right place. My first tought was something like 

    (sort (cons newelt list) #'<)

However, given that `list` is already sorted, only one insertion is
really needed, which means this solution could be horribly unsuitable
depending on the algorithm used by `sort`.

So, **which is the algorithm that `sort` uses?**

Would I be better off doing something like the following?

    (let ((tail list))
      ;; The first element is never less-than
      (while (and tail (< newelt (cadr tail)))
        (setq tail (cdr tail)))
      (setcdr tail (cons newelt (cdr tail)))
      list)