function warn(format) {
  {
    {
      for (var _len = arguments.length, args = new Array(_len > 1 ? _len - 1 : 0), _key = 1; _key < _len; _key++) {
        args[_key - 1] = arguments[_key];
      }

      printWarning('warn', format, args);
    }
  }
}
Forces an update. This should only be invoked when it is known with
certainty that we are **not** in a DOM transaction.

You may want to call this when you know that some deeper aspect of the
component's state has changed but `setState` was not called.

This will not invoke `shouldComponentUpdate`, but it will invoke
`componentWillUpdate` and `componentDidUpdate`.

@param {?function} callback Called after update is complete.
@final
@protected