Add back code comment

Author: cdce8p

pylint/extensions/private_import.py

@@ -199,7 +199,7 @@ def _populate_type_annotations_annotation(
             case nodes.Name() if node.name not in all_used_type_annotations:
                 all_used_type_annotations[node.name] = True
                 return node.name  # type: ignore[no-any-return]
-            case nodes.Subscript():
+            case nodes.Subscript():  # e.g. Optional[List[str]]
                 # slice is the next nested type
                 self._populate_type_annotations_annotation(
                     node.slice, all_used_type_annotations