Scheme Programming Question!

interleave3 takes three lists of atoms and returns a list where the elements are interleaved in order in the pattern: (list1, list2, list3, list1, list2, list3, ...). The lists do not have to be the same length.

> (interleave3 '(a b c d) '(1 2) '(P Q R S T U)) (a 1 P b 2 Q c R d S T U)