Write a function index(elem, seq) that takes as inputs an element elem and a sequence seq, and that uses recursion (i. e., that calls itself recursively) to find and return the index of the first occurrence of elem in seq. the sequence seq can be either a list or a string. if seq is a string, elem will be a single-character string; if seq is a list, elem can be any value. don’t forget that the index of the first element in a sequence is 0.