code: public Node after(Node node) {
          Validate.notNull(node);
          Validate.notNull(parentNode);
  
          parentNode.addChildren(siblingIndex + 1, node);
          return this;
      }
docs: Insert the specified node into the DOM after this node (i.e. as a following sibling).
  @param node to add after this node
  @return this node, for chaining
  @see #before(Node)