x3 :: Integer -> (Maybe Integer, Maybe Integer)
x3 n = (a, a)
  where a = z' n


-- 22.11 Chapter Exercises
x3 :: Integer -> (Maybe Integer, Maybe Integer)
x3 n = (a, a)
  where a = z' n


-- 22.11 Chapter Exercises
x3 n = (a, a)
  where a = z' n


-- 22.11 Chapter Exercises