docs: function(fragment) {
      if ("production" !== process.env.NODE_ENV) {
        if (canWarnForReactFragment) {
          // If it is the opaque type, return the keyed object.
          if (fragment[fragmentKey]) {
            return fragment[fragmentKey];
          }
          // Otherwise, check each property if it has an element, if it does
          // it is probably meant as a fragment, so we can warn early. Defer,
          // the warning to extract.
          for (var key in fragment) {
            if (fragment.hasOwnProperty(key) &&
                ReactElement.isValidElement(fragment[key])) {
              // This looks like a fragment object, we should provide an
              // early warning.
              return ReactFragment.extract(fragment);
            }
          }
        }
      }
      return fragment;
    }