diff --git a/src/python/mitmproxy_addon.py b/src/python/mitmproxy_addon.py
index 416e64a..e37d4ba 100644
--- a/src/python/mitmproxy_addon.py
+++ b/src/python/mitmproxy_addon.py
@@ -4,14 +4,16 @@
 import websockets
 import json
 
+
 async def send_ready_notification() -> None:
     uri = "ws://localhost:8001"
-    logging.info(f'sending mitmproxyReady JSON-RPC notification to {uri}')
+    logging.info(f"sending mitmproxyReady JSON-RPC notification to {uri}")
     async with websockets.connect(uri) as websocket:
-        notification_dto = { "jsonrpc": "2.0", "method": "mitmproxyReady" }
+        notification_dto = {"jsonrpc": "2.0", "method": "mitmproxyReady"}
         data = json.dumps(notification_dto)
         await websocket.send(data)
 
+
 class MitmproxyAddon:
     def running(self) -> None:
         # tell the control API that we’re ready to receive traffic
@@ -26,7 +28,9 @@ def request(self, flow: http.HTTPFlow) -> None:
 
         # (b'Connection', b'Upgrade'), (b'Upgrade', b'websocket')
         intercept = MitmproxyAddon.is_websocket_upgrade_request(flow.request)
-        logging.info(f'MitmproxyAddon {"intercepting" if intercept else "not intercepting"} `request` {flow.request.url}, headers {flow.request.headers}')
+        logging.info(
+            f'MitmproxyAddon {"intercepting" if intercept else "not intercepting"} `request` {flow.request.url}, headers {flow.request.headers}'
+        )
         # pretty_host takes the "Host" header of the request into account,
         # which is useful in transparent mode where we usually only have the IP
         # otherwise.
@@ -38,18 +42,26 @@ def request(self, flow: http.HTTPFlow) -> None:
 
             flow.request.host = "localhost"
             flow.request.port = 8002
-            flow.request.scheme = 'http'
+            flow.request.scheme = "http"
             # TODO understand how port fits into this
-            flow.request.headers['Ably-Test-Host'] = original_host
+            flow.request.headers["Ably-Test-Host"] = original_host
             match original_scheme:
-                case 'http':
-                    flow.request.headers['Ably-Test-Proto'] = 'ws'
-                case 'https':
-                    flow.request.headers['Ably-Test-Proto'] = 'wss'
+                case "http":
+                    flow.request.headers["Ably-Test-Proto"] = "ws"
+                case "https":
+                    flow.request.headers["Ably-Test-Proto"] = "wss"
 
     @staticmethod
     def is_websocket_upgrade_request(request: http.Request) -> bool:
         # TODO this request handling is a bit fragile, the special case for `split` is just to handle the fact that Firefox sends 'Connection: keep-alive, Upgrade'
-        return True if 'Connection' in request.headers and ('Upgrade' in request.headers['Connection'].split(", ")) and 'Upgrade' in request.headers and request.headers['Upgrade'] == 'websocket' else False
+        return (
+            True
+            if "Connection" in request.headers
+            and ("Upgrade" in request.headers["Connection"].split(", "))
+            and "Upgrade" in request.headers
+            and request.headers["Upgrade"] == "websocket"
+            else False
+        )
+
 
 addons = [MitmproxyAddon()]