define the parameters clearly

lmdeploy/serve/vl_async_engine.py

@@ -1,9 +1,11 @@
 # Copyright (c) OpenMMLab. All rights reserved.
 import asyncio
-from typing import Dict, List, Optional, Tuple, Union
+from typing import Dict, List, Literal, Optional, Tuple, Union
 
 import PIL
 
+from lmdeploy.messages import (PytorchEngineConfig, TurbomindEngineConfig,
+                               VisionConfig)
 from lmdeploy.pytorch.check_env import try_import_deeplink
 from lmdeploy.serve.async_engine import AsyncEngine
 from lmdeploy.utils import get_logger
@@ -19,17 +21,23 @@
 class VLAsyncEngine(AsyncEngine):
     """Visual Language Async inference engine."""
 
-    def __init__(self, model_path: str, **kwargs) -> None:
-        vision_config = kwargs.pop('vision_config', None)
-        backend_config = kwargs.get('backend_config', None)
-        self.backend = kwargs['backend']
-        if self.backend == 'pytorch':
+    def __init__(self,
+                 model_path: str,
+                 backend: Literal['turbomind', 'pytorch'] = 'turbomind',
+                 backend_config: Optional[Union[TurbomindEngineConfig,
+                                                PytorchEngineConfig]] = None,
+                 vision_config: Optional[VisionConfig] = None,
+                 **kwargs) -> None:
+        if backend == 'pytorch':
             try_import_deeplink(backend_config.device_type)
         self.vl_encoder = ImageEncoder(model_path,
-                                       self.backend,
+                                       backend,
                                        vision_config,
                                        backend_config=backend_config)
-        super().__init__(model_path, **kwargs)
+        super().__init__(model_path,
+                         backend=backend,
+                         backend_config=backend_config,
+                         **kwargs)
         if self.model_name == 'base':
             raise RuntimeError(
                 'please specify chat template as guided in https://lmdeploy.readthedocs.io/en/latest/inference/vl_pipeline.html#set-chat-template'  # noqa: E501