comparing 2 nested arrays in PHP

diffdata

function diffdata($legacy,$shiny) {
    $delta=array();
    foreach ($legacy as $key => $oldval){
        $newval = $shiny[$key];
        if ($oldval==$newval){
            $delta[$key]="✅";
        } else if (is_array($oldval) && is_array($newval)){
            $delta[$key] = diffdata($oldval,$newval);
        } else {
            $delta[$key]="❌ expected: $oldval<br>❌ returned: $newval";
        }        
    }
    return $delta;
}