In LISP, Code the function (duplicateN lis N) which duplicates each atom at the top level N times. If there is a list at the top-level, it isn't duplicated, but it is included in the result.

Hint: APPEND could be useful.

Examples:

> (duplicateN ' (A B C) 2)

(A A B B C C)

> (duplicateN ' (A B C) 3)

(A A A B B B C C C)

> (duplicateN ' (GUM (HAS BEEN) CHEWED) 2)

(GUM GUM (HAS BEEN) CHEWED CHEWED)