code: function Node(properties) {
  
      // Possible Properties
      var node = {
        id: properties.id,
        label: properties.label
      };
  
      if (properties.viz)
        node.viz = properties.viz;
  
      if (properties.attributes)
        node.attributes = properties.attributes;
  
      return node;
    }
docs: Parser Core Functions
  ----------------------
  
  The XML parser's functions themselves.
   
  Node structure.
  A function returning an object guarded with default value.
  
  @param  {object} properties The node properties.
  @return {object}            The guarded node object.