typing: make Optional parameters explicit

rather than implicitly setting a parameter `Optional[foo]`, by simply
assigning it `None`, we make it explicit.
This will be encouraged in newer mypy releases, and is currently
enforced through `--strict`, so let's get going!

Author: igalic

iocage/lib/Filter.py

@@ -116,7 +116,7 @@ def _filter_string_has_globs(self, filter_string: str) -> bool:
         return False
 
     def _split_filter_values(self, user_input: str) -> typing.List[str]:
-        values: List[str] = []
+        values: typing.List[str] = []
         escaped_comma_blocks = map(
             lambda block: block.split(","),
             user_input.split("\\,")
@@ -163,7 +163,7 @@ def __init__(
                 typing.Iterable[typing.Union[Term, str]]
             ]=None) -> None:
 
-        data: List[Union[Term, str]] = []
+        data: typing.List[typing.Union[Term, str]] = []
 
         if terms is not None:
 
@@ -208,7 +208,7 @@ def match_key(self, key: str, value: str) -> bool:
 
         return True
 
-    def _parse_term(self, user_input: str) -> List[Term]:
+    def _parse_term(self, user_input: str) -> typing.List[Term]:
 
         terms = []