On isSearchTree

[kwanghoon]

LearningHaskell_Exercises/HaskellExercises03/test/Spec.hs

Line 100 in 703d3d5

isSearchTreeProp :: E3.Tree Int -> Bool

I got a test failure on isSearchTree as follows:
test/Spec.hs:134:5:
4) isSearchTree isSearchTree should only return true when the flattened tree is sorted
Falsified (after 2 tests):
Node 1 (Leaf (-1)) (Leaf 1)

However, the counterexample is not a search tree where 1 >= -1 but not 1 < 1.

• Node 1 (Leaf (-1)) (Leaf 1)

@kwanghoon