Custom Taxonomy Tree view

I have been trying google for this, but not so easy to search for. I have a custom hierarchical taxonomy, something along the lines of:

Chainsaws
- Electric
- Petrol
- Other
Grasscutters
- Electric
- Petrol
- Other

What I need to do is create an index page, retaining the hierarchical structure.

The closest I have come to doing it is with:

$products = get_terms('product-type');
foreach ($products as $product) {
      $out .= $product->name;
}

But this just shows the ones in use, and loses it hierarchy 🙁

Any insights are very welcome.

Thanks in advance

Andy

<?php
$args = array(
  'taxonomy'     => 'product-type',
  'hierarchical' => true,
  'title_li'     => '',
  'hide_empty'   => false
);
?>

<ul>
<?php wp_list_categories( $args ); ?>
</ul>

You can use the wp_list_categories function also for taxonomies. http://codex.wordpress.org/Template_Tags/wp_list_categories