code: protected void visitedNode(Node visited, String value) {
          levels.getLast().trackNode(visited, value);
      }
docs: Invoked by {@link #visited visited} when visited is an element,
  text, CDATA section, comment or processing instruction.
  
  @param visited the visited node - Unit tests call this with
  null values, so it is not safe to assume it will never be null.
  It will never be null when the {@link #visited visited} method
  delegates here.
  @param value the local name of the element or an XPath
  identifier matching the type of node.