code: public synchronized void addComment(String comment) throws IOException {
  		// reject modification of already closed node
  		if(isOpen==false) {
  			throw new IOException("Attempted to add comment child node to already closed tag '" + name + "'!");
  		}
  		if(lastChildNode==null) {
  			// no child nodes yet, close opening tag
  			writer.write(">");
  		} else {
  			lastChildNode.close();
  		}
  		// comment starts in new line
  		writer.write("\n");
  		SXCommentNode commentNode = new SXCommentNode(comment, writer, tabLevel+1, tabString);
  		lastChildNode = commentNode;
  	}
docs: Adds a comment to this node.
  <b>WARNING:</b> This will close the last added child node, if applicable!
  <b>NOTICE:</b> Syntactically spoken, comments act like child nodes.
  This means, they are treated just like child nodes with respect to indentation
  and embedding them into the document. Therefore, if you want to add a comment to
  a specific node, it is advised to add the comment to this node's supernode in
  advance. This procedure will preserve correct formatting of the resulting document.
  
  @param comment Text of the comment to be added (without leading and trailing
  XML-style comment indicators!).