For this item consider the problem of finding the concatenation of even-lengthed strings from a list, where the notation sll t means the concatenation of strings s and t in that order and the simple function len(s) 20 returns the length (number of characters) on string s. Concatenation of Al1 Even-Lengthed Strings in a List (CONCATEVEN) Input: S[a...b] list of strings Output: c = S[ill 11 ll sli,nl where