Get all terms/slugs - used, not used & in hierarchical order

Question

I need to get all the slugs/terms - those that are used & those that are not. It's hierarchical (3-4 levels).

How to get all (used & not used) terms/slugs in hierarchical order?

This code returns 1. level slugs & ONLY other levels that ARE USED:

 $locations = get_terms('location', array( 'orderby' => 'slug', 'parent' => 0, 'hide_empty' => false) ); 

This code returns a mess - hierarchy is all off & it's a big mess:

 $locations = get_terms('location', array( 'orderby' => 'slug', 'hide_empty' => false) ); 

Answer 1

Try this.

$locations = get_terms( 'location', 'hide_empty=0&orderby=term_group' );

The codex says to avoid using term_group but it should be fine. It was never fully implementet but, according to others, its used quite often.