shuffle
Cons
x
xs
Cons
x
shuffle
reverse
xs
reverse
Cons
x
xs
append
reverse
xs
Cons
x
Nil
append
Cons
x
xs
ys
Cons
x
append
xs
ys
shuffle
Nil
Nil
reverse
Nil
Nil
append
Nil
ys
ys
goal
xs
shuffle
xs
shuffle
1
Cons
2
reverse
1
append
2
Nil
0
goal
1
INNERMOST