Return 204, no content

wmn.py

@@ -17,7 +17,7 @@ with open("config.yml", 'r') as ymlfile:
     cfg = yaml.safe_load(ymlfile)
 
 
-@application.route('/matrix', methods=['POST'])
+@application.route('/matrix', methods=("POST",))
 def notify():
     channel = request.args.get('channel')
     if channel is None or len(channel) == 0:
@@ -50,4 +50,5 @@ def notify():
                        body=f"{username} pushed {len(commit_messages)} commits to {project_name}\n{text_commits}\n",
                        msgtype="m.notice")
 
-    return ""
+    # see Flask.make_response, this is interpreted as (body, status)
+    return "", 204