add_flash_types

# File actionpack/lib/action_controller/metal/flash.rb, line 14
      def add_flash_types(*types)
        types.each do |type|
          next if _flash_types.include?(type)

          define_method(type) do
            request.flash[type]
          end
          helper_method type

          self._flash_types += [type]
        end
      end