def difftool_launch_with_head(filenames, staged, head):
 if (head == u'HEAD'):
  left = None
 else:
  left = head
 difftool_launch(left=left, staged=staged, paths=filenames)

def difftool_launch_with_head ( filenames , staged , head ) : if ( head == u'HEAD' ) : left = None else : left = head difftool_launch ( left = left , staged = staged , paths = filenames )
launch difftool against the provided head .