Formatting

pytube/cli.py

@@ -226,7 +226,9 @@ def _download(
     sys.stdout.write("\n")
 
 
-def unique_name(base: str, subtype: str, video_audio: str, target: str) -> str:
+def unique_name(
+    base: str, subtype: Optional[str], video_audio: str, target: str
+) -> str:
     """
     Given a base name, the file format, and the target directory, will generate
     a filename unique for that directory and file format.