Houdini-style for-each and do-while "compounds" in Maya node editor?

I stumbled across something that I’ve only ever dreamed of, and I want to know if anyone has insight on it: in the hotkey editor of maya2018.3, there are some specific node editor commands of “Node Editor create compound”, “Node Editor create for-each compound”, etc. Ctrl-G is actually assigned by default.

Unfortunately, the provided scripts don’t seem to do anything. No new DG or DAG nodes created, no magic subnets suddenly transforming the user experience.

Is this just another “speculative feature”, or is there actually a hidden world that has been around all this time?

I think this stuff is there by mistake from upcoming features… never heard of for loops or compounds in the maya node editor