<?php

function Gene () {
  yield 1;
  yield 2;
}

$obj = Gene();

foreach ($obj as $val) {
    echo $val * 3;
}

foreach ($obj as $val) {
    echo $val * 2;
}

<?php

function Gene () {
  yield 1;
}

$Generator = Gene();

foreach ($Generator as $val) {
    echo $val * 3;
    break;
}

foreach ($obj as $val) {
    echo $val * 2;
}

<?php

class A { 
  public int $age;
}

class B {
  public A $a;
}

$a = new A;
$b = new B;


$a->age = 0;
$b->a = $a;
$b->a->age = 5;
$a->age = 10;


echo $b->a->age; // ??????????