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.