title: Generating an animated GIF in Python
body: <p>I'm trying to generate an animated GIF using  images2gif.py (pastebin to the most recent verson : bit.ly/XMMn5h ). </p>
  
  <p>I'm using this Python script: </p>
  
  <pre><code>__author__ = 'Robert'
  from images2gif import writeGif
  from PIL import Image
  import os
  
  file_names = sorted((fn for fn in os.listdir('.') if fn.endswith('.gif')))
  #['animationframa.png', 'animationframb.png', ...] "
  
  images = [Image.open(fn) for fn in file_names]
  
  size = (150,150)
  for im in images:
      im.thumbnail(size, Image.ANTIALIAS)
  
  print writeGif.__doc__
  
  filename = "my_gif.GIF"
  writeGif(filename, images, duration=0.2)
  </code></pre>
  
  <p>However, I am getting the following error:</p>
  
  <pre><code>File "C:\Python27\lib\images2gif.py" , line 418, in writeGifToFile
  globalPalette = palettes[ occur.index(max(occur)) ] ValueError: max() 
  arg is an empty sequence
  </code></pre>
  
  <p>It seems to me that occur is empty. What is wrong, and is there a better way?</p>