Annotations do not change runtime behavior.
This commit *only* adds annotations.

Note: __init__ does not need its return type annotated, as it is special.
https://mypy.readthedocs.io/en/stable/class_basics.html#annotating-init-methods



Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Eduardo Habkost <ehabkost@redhat.com>
Reviewed-by: Cleber Rosa <crosa@redhat.com>
Message-Id: <20201009161558.107041-20-jsnow@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>