# Given an English string with alphanumeric characters, encode it by changing each
# alphabetic by its numeric position, and each digit from 1 though 9 by its equivalent position
# in the alphabets (i.e., 1 -> 'a', 2 -> 'b', etc.). zero will be encoded as 'o'. The input string
# will contain lowercase letters only. For simplicity, assume that the input string will
# include alphanumeric characters only.