# File lib/timeliness/definitions.rb, line 164
      def add_formats(type, *add_formats)
        formats = send("#{type}_formats")
        options = add_formats.last.is_a?(Hash) ? add_formats.pop : {}
        before  = options[:before]
        raise FormatNotFound, "Format for :before option #{before.inspect} was not found." if before && !formats.include?(before)

        add_formats.each do |format|
          raise DuplicateFormat, "Format #{format.inspect} is already included in #{type.inspect} formats" if formats.include?(format)

          index = before ? formats.index(before) : -1
          formats.insert(index, format)
        end
        compile_formats
      end