code: function(node, symbolizer) {
          var options = symbolizer.vendorOptions;
          if (options) {
              for (var key in symbolizer.vendorOptions) {
                  this.writeNode("VendorOption", {
                      name: key, 
                      value: symbolizer.vendorOptions[key]
                  }, node);
              }
          }
          return node;
      }
docs: Method: addVendorOptions
  Add in the VendorOption tags and return the node again.
  
  Parameters:
  node - {DOMElement} A DOM node.
  symbolizer - {Object}
  
  Returns:
  {DOMElement} A DOM node.