root node                
                                             
                                             
                                             
                                             
                    some first level node    
                                             
                                             
                                             
                                             
                                             
                    second level node        
                                             
                                             
                                             
                                             
                    another second level node
                                             
                                             
                                             
                                             
                                             
                    another first level node