Merge pull request google#543 from google/google_sync

Google sync

Merge pull request google#532 from google/google_sync

Google sync

Merge pull request google#517 from google/google_sync

Do a PyPI release of the implicit Optional change.

Merge pull request google#506 from google/google_sync

Google sync

Merge pull request google#498 from google/google_sync

Google sync

Merge pull request google#490 from google/google_sync

Do another PyPI release for a typeshed bug fix.

Merge pull request google#487 from google/google_sync

Update pytype CHANGELOG and __version__ for PyPI release.

Merge pull request google#478 from google/google_sync

Google sync

Merge pull request google#468 from google/google_sync

Google sync

Merge pull request google#462 from google/google_sync

Google sync