The function is given two strings t - template, s - to be sorted. Sort the characters in s such that if the character is present in t then it is sorted according to the order in t and other characters are sorted alphabetically after the ones found in t.
custom_sort("edc", "abcdefzyx") ➞ "edcabfxyz"
custom_sort("fby", "abcdefzyx") ➞ "fbyacdexz"
custom_sort("", "abcdefzyx") ➞ "abcdefxyz"
custom_sort("", "") ➞ ""The characters in t and s are all lower-case.