-Write the fringe-enumeration function. It should work on the implementation of
-trees you designed in the previous step.
+Write the fringe-enumeration function. It should work on the
+implementation of trees you designed in the previous step, and it
+should make use of the list comparison function you wrote for question
+2. Thus you'll have to make sure you only use Church numerals as the
+labels of your leaves, though nothing enforces this self-discipline.