docs: def rerender_options(options):
      """Helper function to re-render command-line options.
  
      This assumes that command-line options use the same name as their
      key in the options dictionary.
      """
      args = []
      for name,value in options.iteritems():
          name = name.replace("_","-")
          if value is None:
              pass
          elif isinstance(value,bool):
              if value:
                  args.append("--%s" % (name,))
          elif isinstance(value,list):
              for item in value:
                  args.append("--%s=%s" % (name,item))
          else:
              args.append("--%s=%s" % (name,value))
      return " ".join(args)