The following gif demonstrates folding:

  • If they ever roll out plugins, or whatever. There’s a lot of functionality piled up behind that.

    Edit: I was wrong. It’s going to be in core. It’s just been “in progress” for two years because (a) there have been prerequisite blockers slowly getting implemented, (b) it’s hard, in part because of other Helix features like multiple cursors, and © the guy implementing it (and who can implement it is, in his words, limited to a couple of people with deep Helix knowledge) hasn’t had time.