20: Swift Migrator
- Bug of the week: https://bugs.swift.org/browse/SR-4088
- Ted’s email: https://lists.swift.org/pipermail/swift-dev/Week-of-Mon-20170605/004751.html
- Migrator: https://github.com/apple/swift/tree/master/lib/Migrator
- Migrating to Swift 4: https://swift.org/migration-guide/, https://help.apple.com/xcode/mac/current/#/deve838b19a1
