Online PHP editor | output for bq2df

<?php class test { private $whatever = false; public function __construct() { $a = iterator_to_array($this->firstIterator()); $b = iterator_to_array($this->secondIterator($this->firstIterator())); $c = iterator_to_array($this->thirdIterator($this->firstIterator())); $this->whatever = true; $d = iterator_to_array($this->firstIterator()); $e = iterator_to_array($this->secondIterator($this->firstIterator())); $f = iterator_to_array($this->thirdIterator($this->firstIterator())); var_dump([$a, $b, $c, $d, $e, $f]); } public function firstIterator(): \Iterator { yield 'a'=> 1; yield 'b'=> 2; yield 'c'=> 3; } public function secondIterator(\Iterator $first): \Iterator { if ($this->whatever === true) { return $first; } foreach($first as $key=>$value) { yield $key => $value * $value; } } public function thirdIterator(\Iterator $first): \Iterator { if ($this->whatever === true) { return $first; } return $this->thirdSubIterator($first); } public function thirdSubIterator(\Iterator $first): \Iterator { foreach($first as $key=>$value) { yield $key => $value * $value; } } } new test();