Debug/Learn Recursion of an Object

I am a bit new to Objects and Recursion Any push in the right direction is appreciated Generated from Pear's mimedecode, I have an object whose print_r is: http://www.siren.cc/dev/object.txt The function below will correctly traverse the object and find the 'correct' node. Unfortunately, it is a little beyond my understanding at present. :( Is there a way to debug the below function to echo how it is traversing the object ? For example, how would I echo the key names and values while it is traversing ? The hope is that something will click and I'll finally wrap my brain around this many thanks function getBody(&$part, $primary = 'text', $secondary = 'plain') { $body = false; if (is_array($part)) { foreach($part as $subpart) { if (! $body = getBody($subpart, $primary, $secondary)) { continue; } else { return $body; } } } else { if (isset($part->parts)) { return getBody($part->parts, $primary, $secondary); } else { if ($part->ctype_primary == $primary && $part->ctype_secondary == $secondary) { return($part->body); } } } return $body; }