http://joychester.blogspot.com/2011/03/reverseasentencewithrubycode.html

reverse a sentense

#!/usr/bin/python
import string

def reverse(sentence):
    stack = []
    word = ''
    for char in sentence:
        if char in string.punctuation or char == ' ':
            if word is not None:
                stack.append(word)
                word = ''
            stack.append(char)
        else:
            word += char

    output = ''
    while len(stack) > 0:
        output += stack.pop()

    return output

if __name__ == "__main__":
    print reverse("One, Two, Three, Four.")