Espero que os guste comenten.
  
escalera_data.php 
 Código PHP:
    <?php
class escalera_data {
  private $data= array();
   public function data_fun(){
  echo "<br>Accediendo data_fun() <b> Acceso del Nivel: 0</b>";
          function arrays(){
            echo "<br>Accediendo arrays() <b> Acceso del Nivel: 0</b>";
               $entrada=@$_GET['true'];
                                      if($entrada !== 'true'):
                                        function arrays2(){
                                            echo "<br>Esto es privado ¡Los datos estas reservados aqui.! <b> Acceso del Nivel: 1</b>";
                                            echo "<br>¿Quieres consultar datos? Haz click aqui: <a href='?metodos=metodos&true=true'>Aceptar</a> ";
                                            //set get  isset
                                            include('private/metodos.php');
                                                    }
                                           else:
                                                    function arrays2(){
                                                      echo "<br>Usted acaba de acceder a los datos privado <b> Acceso del Nivel: 2</b> ";
                                                      echo "<br> ¿Quieres volverlo privado? Haz click aqui: <a href='?true=false'>Aceptar</a>' ";
                                                           @include('private/'.@$_GET["metodos"].'.php');
                                                           $imprime=new escalera_magica_2();
                                                            $name_value=$imprime->name='valor2';
                                                           echo $imprime->name;
                                                           var_dump(isset( $name_value));
                                                           echo "<br>";
                                                           echo "Eliminando.....";
                                                           unset($name_value);
                                                           echo "<br>";
                                                           echo "Eliminado.";
                                                           echo "<br>";
                                                           var_dump(isset( $name_value));
                                                           echo "<br>";
                                                             //return data
                                                           echo "<br>Deseo acceder directamente al nivel: 3 <b> Acceso del Nivel: 2</b> ";
                                                           echo "<br> ¿Quieres acceder? Haz click aqui: <a href='?metodos=metodos&nivel=3&true=true'>Aceptar</a>' ";
                                                                                           function niveles() {
                                                                               echo "Accediendo a niveles:";
                                                                               $nivel=@$_GET['nivel'];
                                                                                                               if($nivel !== '3'):
                                                                                                                                    function nivel_3() {
                                                                                                                              //datos nivel 3
                                                                                                                                  echo "<br>Esto es privado ¡Los datos estas reservados aqui.! <b> Acceso del Nivel: 3</b>";
                                                                                                                                echo "<br>¿Quieres consultar datos? Haz click aqui: <a href='?metodos=metodos&nivel=3&true=true'>Aceptar</a> ";
                                                                                                                                                                          //set get  isset
                                                                                                                            ##### include('private/metodos2.php');
                                                                                                                                echo "<i>Esta vacio no hay datos disponibles...</i>";
                                                                                                                            }//nivel 3
                                                                                                                              else:
                                                                                                                                      function nivel_3 (){
                                                                                                                                        #####llamada de datos nivel 3
                                                                                                                                      echo "<br>Fin de nivel no hay mas datos <b> Acceso del Nivel: 3</b> ";
                                                                                                                                      echo "<br> ¿Desea Reiniciar? Haz click aqui: <a href='?true=false'>Aceptar</a>' ";
                                                                                                                                      echo "<i>No existe llamada de datos...</i>";
                                                                                                                                      }  //nivel 4
                                                                                                                                endif;
                                                                                                         }//niveles
                                                                                                         niveles();
                                                                                                         nivel_3();
                                                          }//array 2
                                             endif;
                        }
             arrays();
             arrays2();
       }
 }
?>
  <?php
 //imprime
 $imprime=new escalera_data();
 $imprime=$imprime->data_fun();
?>    
  
private/metodos.php  
 Código PHP:
    <?php
class escalera_magica_2 {
  private $data= array();
public function __set($name,$arguments){
  echo "<br>Estableciendo '$name' a '$arguments'<br>";
$this->data[$name]=$arguments;
echo "<br>__set data name : argumentos: ".$this->data[$name];
}
public function __get($name){
echo "<br>consulando get<br>";
if( array_key_exists($name,$this->data)  ){ echo "<br>Existe get name<br>"; }else{ echo "No existe get name<br>"; }
}
  public function __isset($name){
    echo   "<br>Esta definido name : ".$this->data[$name];
  return false;
  isset($this->data[$name]) ;
 return true;
  }
  public function __unset($name){
  unset($this->data[$name]);
  echo  "Eliminado .";
    }
}//escalera magica 2
 ?>