We used to be able to use symbols in search, but that now appears to be broken.
I'd expect a search for
[python] += list to return a result, but instead the search engine appears to put quotes around the whole request; the search box shows the search has been replaced with
"[python] += list" and the specific result I was looking for doesn't appear among the returned questions.
Using quotes around the symbols do not seem to help here;
[python] "+=" list returns an empty result.