code: function(type, id) {
          var node = document.createElementNS(this.xmlns, type);
          if (id) {
              node.setAttributeNS(null, "id", id);
          }
          return node;    
      }
docs: Method: createNode
  
  Parameters:
  type - {String} Kind of node to draw
  id - {String} Id for node
  
  Returns:
  {DOMElement} A new node of the given type and id