Implemented youtube substitution

twoot.py

@@ -135,7 +135,6 @@ def _remove_trackers_fragment(fragment_str):
     :param query_str: fragment to be cleaned
     :return: cleaned fragment
     """
-
     params_to_remove = {
         "Echobox",
     }
@@ -147,6 +146,19 @@ def _remove_trackers_fragment(fragment_str):
     return fragment_str
 
 
+def _substitute_source(domain):
+    """
+    private function
+    param domain: Domain name to substitute
+    :return: domain or sustitute if applicable
+    """
+    youtube_subst = TOML["options"]["substitution"]["youtube"]
+    if domain == 'youtube.com' and youtube_subst != []:
+        domain = youtube_subst[random.randint(0, len(youtube_subst) - 1)]
+        logging.debug("Replaced youtube.com by " + domain)
+
+    return domain
+
 def clean_url(dirty_url):
     """
     Given a URL, return it with the UTM parameters removed from query and fragment
@@ -160,7 +172,7 @@ def clean_url(dirty_url):
 
     cleaned_url = urlunparse([
         url_parsed.scheme,
-        url_parsed.netloc,
+        _substitute_source(url_parsed.netloc),
         url_parsed.path,
         url_parsed.params,
         _remove_trackers_query(url_parsed.query),