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<?php class A {} class B extends A {} var_dump(is_a('A','B')); var_dump(is_a('B','A')); var_dump(is_subclass_of('A','B')); var_dump(is_subclass_of('B','A')); var_dump(is_subclass_of('A','A'));

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32.27 ms | 402 KiB | 5 Q