Use of PHP instanceof

<?php
class Math{
    static function squared($input){
        echo $input*$input;
    }
}

$math = new Math();
if($math instanceof Math){
    echo 'yes';
}

instanceof checks whether an instance is derived from this class.

The above introduces the use of PHP instanceof, including aspects of the content. I hope it will be helpful to friends who are interested in PHP tutorials.