title: What does "**" mean in python?
body: <blockquote>
    <p><strong>Possible Duplicate:</strong><br>
    <a href="https://stackoverflow.com/questions/36901/what-does-and-do-for-python-parameters">What does ** and * do for python parameters?</a><br>
    <a href="https://stackoverflow.com/questions/287085/what-does-args-and-kwargs-mean">What does *args and **kwargs mean?</a>  </p>
  </blockquote>
  
  
  
  <p>Simple program:</p>
  
  <pre><code>storyFormat = """                                       
  Once upon a time, deep in an ancient jungle,
  there lived a {animal}.  This {animal}
  liked to eat {food}, but the jungle had
  very little {food} to offer.  One day, an
  explorer found the {animal} and discovered
  it liked {food}.  The explorer took the
  {animal} back to {city}, where it could
  eat as much {food} as it wanted.  However,
  the {animal} became homesick, so the
  explorer brought it back to the jungle,
  leaving a large supply of {food}.
  
  The End
  """                                                 
  
  def tellStory():                                     
      userPicks = dict()                              
      addPick('animal', userPicks)            
      addPick('food', userPicks)            
      addPick('city', userPicks)            
      story = storyFormat.format(**userPicks)
      print(story)
  
  def addPick(cue, dictionary):
      '''Prompt for a user response using the cue string,
      and place the cue-response pair in the dictionary.
      '''
      prompt = 'Enter an example for ' + cue + ': '
      response = input(prompt).strip() # 3.2 Windows bug fix
      dictionary[cue] = response                                                             
  
  tellStory()                                         
  input("Press Enter to end the program.")     
  </code></pre>
  
  <p>Focus on this line:</p>
  
  <pre><code>    story = storyFormat.format(**userPicks)
  </code></pre>
  
  <p>What does the <code>**</code> mean? Why not just pass a plain <code>userPicks</code>?</p>