magic method get php

<?php
 
class Person{
 private $firstName;
 
 public function __get($propertyName){
 echo "attempted to read non-existing property: $propertyName 
";
 } 
 public function __set($propertyNane, $propertyValue){
 echo "attempted to write to non-existing property: $propertyNane 
";
 } 
 
}
 
$p = new Person();
 
$p->firstName = 'Doe';
echo $p->firstName;
 
$p->lastName = 'John';
echo $p->lastName;