🏗 Wrap CLI code in main()

Idiomatic `__main__` usage to ease (future) tests and code structure
see: https://docs.python.org/3/library/__main__.html#idiomatic-usage

delarte.py

@@ -1,5 +1,5 @@
 #!/usr/bin/env python3
-# coding:utf-8
+# coding: utf8
 
 """delarte.
 
@@ -88,7 +88,8 @@ def write_subtitles(m3u8_url, base_name):
             return f.name
 
 
-# command line arguments
+def main():
+    """CLI function, options passed as arguments."""
     (UI_LANG, _, STREAM_ID, SLUG) = urlparse(sys.argv[1]).path[1:-1].split("/")
     VERSION = " ".join(sys.argv[2:])
 
@@ -112,5 +113,18 @@ M3U8_URL, VERSION_NAME = VERSIONS[VERSION]
     write_subtitles(M3U8_URL, FILENAME)
 
     subprocess.run(
-    [FFMPEG, "-i", M3U8_URL, "-c", "copy", "-bsf:a", "aac_adtstoasc", f"{FILENAME}.mp4"]
+        [
+            FFMPEG,
+            "-i",
+            M3U8_URL,
+            "-c",
+            "copy",
+            "-bsf:a",
+            "aac_adtstoasc",
+            f"{FILENAME}.mp4",
+        ]
     )
+
+
+if __name__ == "__main__":
+    sys.exit(main())