code: function onChildRoutes(error, childRoutes) {
        if (error) {
          callback(error);
        } else if (childRoutes) {
          // Check the child routes to see if any of them match.
          matchRoutes(childRoutes, location, function (error, match) {
            if (error) {
              callback(error);
            } else if (match) {
              // A child route matched! Augment the match and pass it up the stack.
              match.routes.unshift(route);
              callback(null, match);
            } else {
              callback();
            }
          }, remainingPathname, paramNames, paramValues);
        } else {
          callback();
        }
      }
docs: Either a) this route matched at least some of the path or b) we don't have to load this route's children asynchronously. In either case continue checking for matches in the subtree.