code: function(q) {
          var list = slice(this),
              omittedNodes = xui(q);
          if (!omittedNodes.length) {
              return this;
          }
          return this.filter(function(i) {
              var found;
              omittedNodes.each(function(el) {
                  return found = list[i] != el;
              });
              return found;
          });
      }
docs: not
  ---
  
  The opposite of `has`. It modifies the elements and returns all of the elements that do __not__ match a CSS query.
  
  ### syntax ###
  
  x$( window ).not( selector );
  
  ### arguments ###
  
  - selector `String` a CSS selector for the elements that should __not__ be matched.
  
  ### example ###
  
  Given:
  
  <div>
  <div class="round">Item one</div>
  <div class="round">Item two</div>
  <div class="square">Item three</div>
  <div class="shadow">Item four</div>
  </div>
  
  We can use `not` to select objects:
  
  var divs     = x$('div');          // got all four divs.
  var notRound = divs.not('.round'); // got two divs with classes .square and .shadow