Lint and typing cleanup

test/mypy.ini

@@ -0,0 +1,9 @@
+[mypy]
+ignore_missing_imports = True
+strict_optional = False
+disallow_incomplete_defs = True
+disallow_untyped_defs = True
+warn_unused_configs = True
+warn_unused_ignores = True
+warn_unreachable = True
+disallow_untyped_calls = True