code: function lazyLoadImages() {
    var config = arguments.length > 0 && arguments[0] !== undefined ? arguments[0] : {};
  
    // If we have `srcset` support, initialize the lazyloader.
    /* istanbul ignore else: unreasonable to test browser support just for a no-op */
    if ('srcset' in document.createElement('img')) {
      return initialize(config);
    }
  
    // If there’s no support, return a no-op.
    /* istanbul ignore next: unreasonable to test browser support just for a no-op */
    return function () {
      /* no-op */
    };
  }
docs: The public function to initialize lazyloading
  @param  {Object} config configuration options (see `initialize()`)
  @return {Function}      a function to manually check for images to lazy load