In the past I believe we allowed or even preferred this syntax, but more recently we've moved to preferring PEP8 style generally (with spaces on either side of all operators, including `**`).

There are a few other places where spaces should be added around e.g. `*`. Running flake8 on these will show you where. Also, if it results in a bad line break or poor readability feel free to defend non-PEP8 syntax - PEP8 itself says it's meant to be broken ;)