# File lib/optconfig.rb, line 169
  def option(*args)
    args = args.dup
    if args.last.is_a? Hash
      attr = args.pop
      attr = @default_attr.merge attr
    else
      attr = @default_attr
    end
    args.push attr
    opt = Option.new *args
    opt.name.each do |n|
      raise "option #{n} is already defined" if @options.key? n
      @options[n] = opt
    end
    @option_seq << opt
  end