Replace All Digits with Characters

You are given a 0-indexed string s that has lowercase English letters in its odd indices and digits in its even indices. There is a function shift(c, x), where c is a character and x is a digit, that shifts the character c by x positions to the right in the alphabet. For example, if c = 'a' and x = 2, then shift(c, x) = 'c'.

Return the string after replacing all of its digits with the result of applying shift to each digit.