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run code in 300+ PHP versions simultaneously
<?php $mock = [ 'foo' => null ]; foreach ($mock as &$item) { $item = 'foo'; } $mockCopy = $mock; $mockCopy['foo_copy'] = $mock['foo']; $mockCopy['foo'] = 'bar'; var_dump($mock['foo']);

preferences:
66.33 ms | 402 KiB | 5 Q