functional programming in haskell

3. (a) What is the type of the following unknown4 function? Give the most general type and include any required class constraints (to the best of your knowledge).

> unknown4 ys = not . any (`elem` ys)

(The function any from the prelude is shown at the bottom of this page.)

(b) Give a simple description of what the unknown4 function in part (a) does. Describe what it does, not how it works.

returns true if the list contains an item equal to the first argument

(c) Give a non-trivial test case of the unknown4 function applied to two arguments and show the expected results.