about php manual Classes and Objects (PHP 5) Example#5 Object Assignment

hello. i'm monji. i'm really grateful to your php manual. it helps me to study php. today i think i found the mistake in Classes and Objects (PHP 5) Example#5 Object Assignment. example is <?php $assigned = $instance; $reference =& $instance; $instance->var = '$assigned will have this value'; $instance = null; // $instance and $reference become null var_dump($instance); var_dump($reference); var_dump($assigned); ?> and it say The above example will output: NULL NULL object(SimpleClass)#1 (1) { ["var"]=> string(30) "$assigned will have this value" } but it output NULL NULL NULL i think example should be like this <?php $instance->var = '$assigned will have this value'; $assigned = $instance; $reference =& $instance; $instance = null; // $instance and $reference become null var_dump($instance); var_dump($reference); var_dump($assigned); ?> please check that. i'm sorry for my poor english.