    # File lib/action_controller/dispatcher.rb, line 104
        def call(env)
          if @@cache_classes
            @app.call(env)
          else
            Reloader.run do
              # When class reloading is turned on, we will want to rebuild the
              # middleware stack every time we process a request. If we don't
              # rebuild the middleware stack, then the stack may contain references
              # to old classes metal classes, which will b0rk class reloading.
              build_middleware_stack
              @app.call(env)
            end
          end
        end