Seems Simple: Add Page Template Slug to body_class()?

Noob here. I cannot figure out how to add the page template slug to my body classes.

I found body_class() in extras.php, and I’m familiar with get_page_template_slug…but I’m unsure of the syntax of how to add it to the array while leaving get_permalink() in there as well. I tried a few approaches and none added the page template slugs to the body classes. Help?