# Downey, A. (2015). Think Python: How to think like a computer scientist. Needham, Massachusetts: Green Tree Press. def histogram(s): d = dict() for c in s: if c not in d: d[c] = 1 else: d[c] += 1 return d Copy the code above into your program but write all the other code for this assignment yourself. Do not copy any code from another source.