Clean Alpha Channel

Situation: alpha channel will get fatter and fatter while editing each AOVs and merge (plus) them together

Solution: save the original alpha before shuffle all nodes.
// Ps. script for shuffle all AOVs (originally from: http://vfxjimmy.blogspot.com/2014/02/shuffle-out-all-channels-script.html)

nodes = nuke.selectedNodes()
for node in nodes:
 if node.Class() == 'Read':
  channels = node.channels()
  layers = list( set([channel.split('.')[0] for channel in channels]) )
  layers.sort()
  if 'rgba' in layers:
   layers.remove('rgba')
  for layer in layers:
   shuffleNode = nuke.nodes.Shuffle(label=layer,inputs=[node])
   shuffleNode['in'].setValue( layer )
   shuffleNode['postage_stamp'].setValue(True)
 else:
  pass