Replaced set |= operator with update() to avoid unneeded temporary set

[jdufresne]

No description provided.

[charettes]

You can remove the keys() call as iter(dict.keys()) yields the same results as iter(dict). That is update(base.__dict__).

[ngnpope]

Just out of interest, dict.keys() is a set-like object providing a view on a dictionary's keys in Python 3. So the cast to set was only needed for Python 2 where dict.keys() returns a list.

Thus the options here are changing to use set.update() and passing the dictionary as-is - as has already been committed, or to just drop the cast to set as it already is set-like which might look a bit less magic. No strong opinion on this however.

[charettes]

Ditto about the keys() call. I'd also try to avoid cloaking the dict builtin while you are around.

set(chain.from_iterable(dict_ for subcontext in self for dict_ in subcontext))

[jdufresne]

Thanks for the review. Made suggested changes:

• Replaced dict.keys() with bare dict
• Renamed variable dict to d to avoid shadowing builtin