Pete on "Display Categories Assigned to a Post (with hierarchical list styling)"

I have some code that shows how to "Display Categories Assigned to a Post" with each category separated by a
. However, I'd like to display this in a list/hierarchical tree.

Any help greatly appreciated.

Love Pete x

This is what I have...

<?php
$taxonomy = 'category';

// get the term IDs assigned to post.
$post_terms = wp_get_object_terms( $post->ID, $taxonomy, array( 'fields' => 'ids' ) );
// separator between links
$separator = ', ';

if ( !empty( $post_terms ) && !is_wp_error( $post_terms ) ) {

	$term_ids = implode( ',' , $post_terms );
	$terms = wp_list_categories( 'title_li=&style=list&hierarchical=1&echo=1&taxonomy=' . $taxonomy . '&include=' . $term_ids );
	$terms = rtrim( trim( str_replace( '<br />',  $separator, $terms ) ), $separator );

	// display post categories
	echo  $terms;
}
?>

But i'd