code: function createLinkTypeChecker(linkType) {
    var shapes = {
      value: linkType === undefined ? React.PropTypes.any.isRequired : linkType.isRequired,
      requestChange: React.PropTypes.func.isRequired
    };
    return React.PropTypes.shape(shapes);
  }
docs: Creates a PropType that enforces the ReactLink API and optionally checks the
  type of the value being passed inside the link. Example:
  
  MyComponent.propTypes = {
  tabIndexLink: ReactLink.PropTypes.link(React.PropTypes.number)
  }