code: def merge(args):
      
      p = OptionParser(merge.__doc__)
      p.add_option("--colorlist", default="black,red,pink,blue,green",
                   help="The color palette [default: %default]")
      opts, args = p.parse_args(args)
  
      if len(args) < 1:
          sys.exit(not p.print_help())
  
      colorlist = opts.colorlist.split(",")
      assert len(colorlist) >= len(args), "Need more colors in --colorlist"
  
      g = BiGraph()
      for a, c in zip(args, colorlist):
          g.read(a, color=c)
  
      g.draw("merged.png")
docs: %prog merge graphs
  
      Merge multiple graphs together and visualize.