Python

Loop over the given list of strings to build a result string like this: when a string appears the 2nd,4 th, 6 th, etc. time in the list, append the string to the result. Return the empty string if no string appears a 2nd time. \# problem_fifteen(["a", "b", "a"]) "a" \# problem_fifteen(["a", "b", "a", "c", "a", "d", "a"]) "aa" \# problem_fifteen(["a", "", "a"]) "a" def problem_fifteen(string_list): \# Problem 15 code goes here: return a string