def indexed?
      if @indexed.nil?
        @indexed = false
        ancestors.each do |a|
          if a.respond_to?(:indexed?) and a.indexed?
            @indexed = true
            break
          end
        end
      end
      @indexed
    end
def indexed?
      if @indexed.nil?
        @indexed = false
        ancestors.each do |a|
          if a.respond_to?(:indexed?) and a.indexed?
            @indexed = true
            break
          end
        end
      end
      @indexed
    end
Whenever a Ruby class includes BigIndex::Resource, it'll be considered
 as indexed.

 This method checks whether the current class, as well as any ancestors
 in its inheritance tree, is indexed.

 @return [TrueClass, FalseClass] whether or not the current class, or any
   of its ancestors are indexed.