sortTree (>=) (Branch (Branch (Leaf 4) (Leaf 3)) (Leaf 5)) == (Branch (Branch (Leaf 5) (Leaf 4)) (Leaf 3))
sortTree (<=) (Branch (Branch (Leaf 4) (Leaf 3)) (Leaf 5)) == (Branch (Branch (Leaf 3) (Leaf 4)) (Leaf 5))
sortTree (>) (Branch (Branch (Leaf 4) (Leaf 3)) (Leaf 5)) == (Branch (Branch (Leaf 5) (Leaf 4)) (Leaf 3))
sortTree (>) (Branch (Branch (Leaf 4) (Leaf 3)) (Leaf 4)) == (Branch (Branch (Leaf 4) (Leaf 3)) (Leaf 4))

listSort (>=) [3,2,6,2,1] == [6,3,2,2,1]
listSort (<=) [3,2,6,2,1] == [1,2,2,3,6]

isWellformed (Aut ([(1,[(2,'a')]),(2,[(3,'b')])],1,[2,3])) == True
isWellformed (Aut ([(1,[(2,'a')]),(2,[(3,'b')])],5,[2,3])) == False

accept (Aut ([(1,[(2,'a')]),(2,[(3,'b')])],1,[2,3])) "ab"  == True
accept (Aut ([(1,[(2,'a')]),(2,[(3,'b')])],1,[2,3])) "acb" == Fals