Php / Operators / Bitwise - https://www.minte9.com/php/operators-bitwise-27

index.php

<?php

/**
 * Given the users $role and access $rights ...
 * Check if Mike has admin rights and downgrade him
 * Wrong approach:
 *  if ($is_admin && $can_edit_articles ...
 */
 $rights = (object) ["read"=>1, "write"=>2, "readwrite"=>16, "admin"=> 32];
 $role   = (object) ["jim"=>96, "mike"=>32];

/**
 * SOLUTION
 */ 
echo $role->mike & 32; // 32

if ($role->mike & 32) {
    $role->mike = $role->mike >> 1;
}

echo $role->mike; // 16