code: function getImageItem() {
    var item = document.createElement('li');
    item.className = 'is-loading';
    var img = document.createElement('img');
    var size = Math.random() * 3 + 1;
    var width = Math.random() * 110 + 100;
    width = Math.round( width * size );
    var height = Math.round( 140 * size );
    var rando = Math.ceil( Math.random() * 1000 );
    // 10% chance of broken image src
    // random parameter to prevent cached images
    img.src = rando < 100 ? '//foo/broken-' + rando + '.jpg' :
      // use picsum for great random images
      'https://picsum.photos/' + width + '/' + height + '/' + '?random';
    item.appendChild( img );
    return item;
  }
docs: return an <li> with a <img> in it