Is there a convenient way to “collapse” the view of multiple, possibly nested, collections in the outliner?

In an Add-On I'm working on, I procedurally generate a modest-to-large number of collections, and often end up with an outliner looks something like this:

I then often find myself tediously clicking the "collapse" arrow one-by-one on each collection, until they're all collapsed, to clean-up my view before doing further work.

Is there a fast way to do this kind of multi-collection outliner-view collapsing? Either a native / built-in or Python solution would be fine.

Ah: I had looked for an option to do this before posting the question, but apparently not hard enough. First, there is a partial answer here, in that using Shift allows (un-)collapsing nested hierarchies:
And, second, the +/- numpad keys allow (un-)collapsing multiple collections, level by level. That this is so is displayed under the View sub-menu, if you right-click a collection in the Outliner (which also provides another non-keyboard-based way of collapsing multiple collections, of course).