Madlibs in Python

"""
madlib2.py
Interactive display of a mad lib, which is provided as a Python format string,
with all the cues being dictionary formats, in the form %(cue)s.

"""

def getCues(formatString):
    keyList = list()
    end = 0
    repetitions = formatString.count('%(')
    for i in range(repetitions):
        start = formatString.find('%(', end) + 2
        end = formatString.find(')', start)
        key = formatString[start : end]
        keyList.append(key) # may add duplicates
    return set(keyList) # removes duplicates: no duplicates in a set


def getUserPicks(cues):
    userPicks = dict()
    for cue in cues:
        prompt = "Enter a specific example for %s: " % cue     
        userPicks[cue] = raw_input(prompt)
    return userPicks   

def tellStory(story):
    cues = getCues(story)
    print cues
    userPicks = getUserPicks(cues)
    print userPicks
    print story % userPicks    

def main():
    originalStory = '''
    
Once upon a time, deep in an ancient jungle, there lived a %(animal)s. 
This %(animal)s liked to eat %(food)s, but the jungle had
very little %(food)s to offer.  

One day, an explorer found the %(animal)s and discovered
it liked %(food)s.  The explorer took the
%(animal)s back to %(city)s, where it could
eat as much %(food)s as it wanted.  

However, the %(animal)s became %(negative adjective)s, so the
explorer brought it back to the jungle, and left it there 
with a large supply of %(food)s. So the %(animal)s was not 
%(negative adjective)s any more.

The End
'''
    tellStory(originalStory)

main()