Online PHP editor | output for fkbOC

<?php set_error_handler( function ($code, $string) { throw new Exception($string, $code); } ); try { interface I1 {} interface I2 {} class A implements I1 { public function fn() { echo 'foo'; } } class B extends A implements I2 { public function fn($arg) { echo $arg; } } } catch (Exception $e) { // ignore } $b = new B(); var_dump($b instanceof I1); // outputs "bool(false)" var_dump($b instanceof I2); // outputs "bool(false)" var_dump(class_implements('B')); // outputs "array(1) { 'I1' => string(2) "I1" }" $b->fn('bar'); // outputs "bar"