# File lib/unobtrusive_flash/controller_mixin.rb, line 52
      def append_flash_to_cookie(existing_cookie, flash, unobtrusive_flash_keys)
        if existing_cookie
          cookie_flash = JSON.parse(existing_cookie) rescue []
        else
          cookie_flash = []
        end

        cookie_flash += sanitize_flash(flash, unobtrusive_flash_keys)

        cookie_flash.uniq.to_json
      end