code: def update(self, node):
          
          self.replace_references(node)
          for c in node.children:
              self.update(c)
          return node
docs: Update the specified I{node} by replacing the I{multiref} references
          with the contents of the referenced nodes and remove the I{href}
          attribute.
          @param node: A node to update.
          @type node: L{Element}
          @return: The updated node
          @rtype: L{Element}