code: function(fn) {
          // we could compress this by using [].forEach.call - but we wouldn't be able to support
          // fn return false breaking the loop, a feature I quite like.
          for (var i = 0, len = this.length; i < len; ++i) {
              if (fn.call(this[i], this[i], i, this) === false)
              break;
          }
          return this;
      }
docs: each
  ----
  
  Element iterator for an XUI collection.
  
  ### syntax ###
  
  x$( window ).each( fn )
  
  ### arguments ###
  
  - fn `Function` callback that is called once for each element.
  
  `element` is the current element
  `index` is the element index in the XUI collection
  `xui` is the XUI collection.
  function( element, index, xui ) {
  `this` is the current element
  }
  
  ### example ###
  
  x$('div').each(function(element, index, xui) {
  alert("Here's the " + index + " element: " + element);
  });