tweak advanced

Signed-off-by: Jim Pryor <profjim@jimpryor.net>

diff --git a/miscellaneous_lambda_challenges_and_advanced_topics.mdwn b/miscellaneous_lambda_challenges_and_advanced_topics.mdwn
index a4ba985..a3d65e2 100644 (file)
--- a/miscellaneous_lambda_challenges_and_advanced_topics.mdwn
+++ b/miscellaneous_lambda_challenges_and_advanced_topics.mdwn
@@ -496,8 +496,8 @@ can use.
        Think about how you'd implement them in a more principled way. You could
        use any of the version 1 -- version 5 implementation of lists as a model.
 
        Think about how you'd implement them in a more principled way. You could
        use any of the version 1 -- version 5 implementation of lists as a model.
 

-       To keep things simple, I recommend starting with the version 3 pattern. And
-       stick to binary trees.
+       To keep things simple, we'll stick to binary trees. A node will either be a
+       *leaf* of the tree, or it will have exactly two children.

 
        There are two kinds of trees to think about. In one sort of tree, it's only
        the tree's *leaves* that are labeled:
 
        There are two kinds of trees to think about. In one sort of tree, it's only
        the tree's *leaves* that are labeled: