Indenting Class record

I’m utilizing the get_categories() operate mixed with a foreach loop, to create an inventory of all of the catgorys in a kind. like so:

$args = array(
                'sort'                     => 'publish',
                'hide_empty'               => 0, //<--IMPORTANT!!
                'hierarchical'             => 1,
                'taxonomy'                 => 'class',
                'pad_counts'               => false );
                $classes = get_categories($args);
                foreach($classes as $class) { 
                        echo '<tr>';
                        echo "<td>$category->title</td>";
                        echo "<td><enter sort='textual content' title='$category->cat_ID'/></td>";
                        echo '</tr>';
                    }

Nevertheless, what I want is for all of the sub classes to be indented, however I can not work out how.

After trying on the documentation Right here it appears that evidently $category->mum or dad parameter, could also be useful, however I can not get it working.

Any assist could be appreciated.