Write the fringe-enumeration function. It should work on the implementation of
trees you designed in the previous step.
-
-(See [[hints/Assignment 4 hint 3]] if you need some hints.)
</OL>
notes](/week3/#index4h2) as a model, construct a pair `Y1` and `Y2` that behave
in the way described.
-(See [[hints/Assignment 4 hint 4]] if you need some hints.)
+(See [[hints/Assignment 4 hint 3]] if you need some hints.)
</OL>