Some of us might believe that a currently legal syntax should only exceptionally be given a new meaning, even if there is no evidence whatsoever that this legal syntax is actually in use. My own belief is more pragmatic. If there's very strong evidence that the syntax is not in use, I'm happy to consider changing the meaning.

I wrote:

The title of this thread includes the phrase 'Stop Iterating' (capitals added). This suggests the syntax
a, b, StopIterating = iterable
where StopIterating is a new keyword that can be used only in this context.

In response Chris wrote:

Hard no. That is currently-legal syntax, and it's also clunky.

Although

a, b, StopIterating = iterable

is currently legal syntax, I believe that no-one has ever used it in Python before today. My evidence is this search, which gives 25 pages.

https://www.google.com/search?q=%22stopiterating%22+python&nfpr=1

These pages found by this search do match "StopIterating", but do not provide an example of their use in Python.

https://stackoverflow.com/questions/19892204/send-method-using-generator-still-trying-to-understand-the-send-method-and

https://julia-users.narkive.com/aD1Uin0y/implementing-an-iterator-which-conditionally-skips-elements

The following are copies of the stackoverflow page.

https://mlink.in/qa/?qa=810675/

https://www.796t.com/post/MmFubjI=.html

https://qa.1r1g.com/sf/ask/1392454311/

Jonathan