instance method nested

# File actionpack/lib/action_dispatch/routing/mapper.rb, line 1208
        def nested
          unless resource_scope?
            raise ArgumentError, "can't use nested outside resource(s) scope"
          end

          with_scope_level(:nested) do
            if shallow?
              with_exclusive_scope do
                if @scope[:shallow_path].blank?
                  scope(parent_resource.nested_scope, nested_options) { yield }
                else
                  scope(@scope[:shallow_path], :as => @scope[:shallow_prefix]) do
                    scope(parent_resource.nested_scope, nested_options) { yield }
                  end
                end
              end
            else
              scope(parent_resource.nested_scope, nested_options) { yield }
            end
          end
        end