You can use a function type as the return type of another function. You do this by writing
a complete function type immediately after the return arrow (->) of the returning function.
The next example defines two simple functions called stepForward and stepBackward. The
stepForward function returns a value one more than its input value, and the stepBackward
function returns a value one less than its input value. Both functions have a type of (Int) ->
Int: