Automate the boring stuff with Python: Comma Code

Question

Currently working my way through this beginners book and have completed one of the practice projects \'Comma Code\' which asks the user to construct a program which:

Answer 1

I was not satisfied with any of the solutions because none handle the case with or, e.g. apples, bananas, or berries

def oxford_comma(words, conjunction='and'):
    conjunction = ' ' + conjunction + ' '

    if len(words) <= 2:
        return conjunction.join(words)
    else:
        return '%s,%s%s' % (', '.join(words[:-1]), conjunction, words[-1])

Otherwise, this solution is more-or-less identical to the one provided by @PM2Ring