call

# File actionpack/lib/action_dispatch/routing/route_set.rb, line 27
        def call(env)
          params = env[PARAMETERS_KEY]
          prepare_params!(params)

          # Just raise undefined constant errors if a controller was specified as default.
          unless controller = controller(params, @defaults.key?(:controller))
            return [404, {'X-Cascade' => 'pass'}, []]
          end

          dispatch(controller, params[:action], env)
        end