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<?php $a = [ 23 => [ 'foo' ], 42 => 'bar', ]; var_dump( filter_var( $a, FILTER_UNSAFE_RAW, FILTER_REQUIRE_ARRAY ) ); var_dump( filter_var( $a[23], FILTER_UNSAFE_RAW, FILTER_REQUIRE_ARRAY ) ); var_dump( filter_var( $a[42], FILTER_UNSAFE_RAW, null ) );

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