The typing module has been available since Python 3.5. Guarding the
import has been unnecessary since dropping Python 2.
Some guards remain to either:
- Avoid circular imports
- Importing objects that are also guarded by typing.TYPE_CHECKING
- Avoid mypy_extensions dependency
The stdlib module has been available since Python 3.5 and the
TYPE_CHECKING constant has been available since 3.5.2.
By using stdlib, this removes the need for pip to maintain its own
Python 2 typing compatibility shim.
Since Python 3.3, the following classes have merged into OSError. They
remain as aliases for backward compatibility.
- EnvironmentError
- IOError
- WindowsError
https://docs.python.org/3/library/exceptions.html#OSError
Python 3 also has subclasses of OSError to help identify more specific
errors. For example, FileNotFoundError. This allows simplifying some
except blocks.