put everything in main(), zero mypy issues

bcao.py

@@ -34,6 +34,7 @@ from PIL import Image
 fully_supported: List[str] = ["ogg", "flac", "mp3", "m4a", "wav"]
 MutagenFile = Union[MP3, FLAC, OggVorbis, mutagen.FileType]
 MutagenTags = Union[mutagen.id3.ID3Tags, mutagen.mp4.Tags, mutagen.oggvorbis.OggVCommentDict]
+args: argparse.Namespace
 
 class SongInfo:
 	tag_lookup: Dict[str, Dict[str, str]] = {
@@ -61,6 +62,7 @@ class SongInfo:
 		if fallbacks is None:
 			die("Couldn't determine fallback tags!")
 			return # needed for mypy
+
 		# set default values for the tags, in case the file is missing any (or all!) of them
 		self.tags: Dict[str, str] = {
 			"track": fallbacks.group("track"),
@@ -210,6 +212,8 @@ def sanitise(in_str: str) -> str:
 		return re.sub(r"[?\\/:|*\"<>]", "_", in_str)
 	return in_str
 
+
+def main():
 	# noinspection PyTypeChecker
 	parser = argparse.ArgumentParser(usage='%(prog)s zip [options]',
 		formatter_class=argparse.RawTextHelpFormatter,
@@ -230,6 +234,7 @@ parser.add_argument('-u', '--unsanitised', dest='sanitise', action='store_false'
 	parser.add_argument('-t', '--threshold', dest='threshold', nargs=1, default=300,
 		help="Maximum acceptable file size for cover art, in kilobytes.\nDefault: %(default)s")
 
+	global args
 	args = parser.parse_args()
 	# convert args.threshold to bytes
 	args.threshold *= 1024
@@ -266,7 +271,7 @@ if song_format not in fully_supported:
 
 	if cover is None:
 		die("Unable to find cover image!")
-	# return # needed for mypy
+		return # needed for mypy
 
 	if args.process_cover != 'n':
 		log("Resizing album art to embed in songs...")
@@ -410,3 +415,6 @@ shutil.move(str(Path(tmp, cover)), str(Path(destination, cover)))
 
 	tmp_dir.cleanup()
 	log("Done!")
+
+if __name__ == "__main__":
+	main()