Oh it looks like I misremembered. I thought the API I had used was something like `set doc [foo parse $input]` and the document would go away when the variable

Oh it looks like I misremembered. I thought the API I had used was something like `set doc [foo parse $input]` and the document would go away when the variable does. I found it, it's the tDOM library, and it was actually `dom parse $xml doc` that does the automatic freeing, whereas `set doc [dom parse $xml]` requires manual deletion. So it probably is using trace.