don’t require websockets

Author: rickwierenga

pylabrobot/liquid_handling/backends/websocket.py

@@ -47,7 +47,7 @@ def __init__(
       raise RuntimeError("The simulator requires websockets to be installed.")
 
     super().__init__(num_channels=num_channels)
-    self._websocket: Optional[websockets.legacy.server.WebSocketServerProtocol] = None
+    self._websocket: Optional["websockets.legacy.server.WebSocketServerProtocol"] = None
     self._loop: Optional[asyncio.AbstractEventLoop] = None
     self._t: Optional[threading.Thread] = None
     self._stop_: Optional[asyncio.Future] = None
@@ -111,7 +111,7 @@ async def handle_event(self, event: str, data: dict):
     if event == "ping":
       await self.websocket.send(json.dumps({"event": "pong"}))
 
-  async def _socket_handler(self, websocket: websockets.legacy.server.WebSocketServerProtocol):
+  async def _socket_handler(self, websocket: "websockets.legacy.server.WebSocketServerProtocol"):
     """ Handle a new websocket connection. Save the websocket connection store received
     messages in `self.received`. """