🏗 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.
 
@@ -88,29 +88,43 @@ def write_subtitles(m3u8_url, base_name):
             return f.name
 
 
-# command line arguments
-(UI_LANG, _, STREAM_ID, SLUG) = urlparse(sys.argv[1]).path[1:-1].split("/")
-VERSION = " ".join(sys.argv[2:])
+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:])
 
-if UI_LANG not in ("fr", "de", "en", "es", "pl", "it") or _ != "videos":
-    raise ValueError("Invalid URL")
+    if UI_LANG not in ("fr", "de", "en", "es", "pl", "it") or _ != "videos":
+        raise ValueError("Invalid URL")
 
-TITLE, VERSIONS = call_api(
-    f"https://api.arte.tv/api/player/v2/config/{UI_LANG}/{STREAM_ID}"
-)
+    TITLE, VERSIONS = call_api(
+        f"https://api.arte.tv/api/player/v2/config/{UI_LANG}/{STREAM_ID}"
+    )
 
-FILENAME = TITLE.replace("/", "-")
+    FILENAME = TITLE.replace("/", "-")
 
-if VERSION not in VERSIONS:
-    print(TITLE)
-    for v, (_, l) in VERSIONS.items():
-        print(f"\t{v} : {l}")
-    exit(1)
+    if VERSION not in VERSIONS:
+        print(TITLE)
+        for v, (_, l) in VERSIONS.items():
+            print(f"\t{v} : {l}")
+        exit(1)
 
-M3U8_URL, VERSION_NAME = VERSIONS[VERSION]
+    M3U8_URL, VERSION_NAME = VERSIONS[VERSION]
 
-write_subtitles(M3U8_URL, FILENAME)
+    write_subtitles(M3U8_URL, FILENAME)
 
-subprocess.run(
-    [FFMPEG, "-i", M3U8_URL, "-c", "copy", "-bsf:a", "aac_adtstoasc", f"{FILENAME}.mp4"]
-)
+    subprocess.run(
+        [
+            FFMPEG,
+            "-i",
+            M3U8_URL,
+            "-c",
+            "copy",
+            "-bsf:a",
+            "aac_adtstoasc",
+            f"{FILENAME}.mp4",
+        ]
+    )
+
+
+if __name__ == "__main__":
+    sys.exit(main())