    # File lib/active_support/core_ext/module/inclusion.rb, line 21
      def included_in_classes
        classes = []
        ObjectSpace.each_object(Class) { |k| classes << k if k.included_modules.include?(self) }

        classes.reverse.inject([]) do |unique_classes, klass|
          unique_classes << klass unless unique_classes.collect { |k| k.to_s }.include?(klass.to_s)
          unique_classes
        end
      end