    # File lib/facets/core/module/attr_tester.rb, line 24
      def attr_tester(*args)
        make = {}
        args.each { |a|
          make["#{a}?".to_sym] = %{
            def #{a}?(true_value=true)
              @#{a} ? true_value : @#{a}
            end
          }
          make["#{a}!".to_sym] = %{
            def #{a}!(switch=Exception)
              if switch == Exception
                @#{a} = !@#{a}
              else
                @#{a} = switch ? true : @#{a}
                self
              end
            end
          }
        }
        module_eval make.values.join("\n")

        return make.keys
      end