def format
      REXML::Element.new("event").tap do |event|
        @attributes.each do |attribute|
          event.elements << attribute.format if attribute.formattable?
        end
      end
    end
def format
      REXML::Element.new("event").tap do |event|
        @attributes.each do |attribute|
          event.elements << attribute.format if attribute.formattable?
        end
      end
    end
Format as a XML element.

 @return [REXML::Element]
   XML element