Add vectorstore type info

langchain/callbacks/manager.py

@@ -1203,7 +1203,6 @@ class CallbackManager(BaseCallbackManager):
         """Run when retriever starts running."""
         if run_id is None:
             run_id = uuid4()
-
         _handle_event(
             self.handlers,
             "on_retriever_start",

langchain/vectorstores/base.py

@@ -454,6 +454,13 @@ class VectorStoreRetriever(BaseRetriever):
 
         arbitrary_types_allowed = True
 
+    @property
+    def lc_serializable(self) -> bool:
+        """
+        Return whether or not the class is serializable.
+        """
+        return True
+
     @root_validator()
     def validate_search_type(cls, values: Dict) -> Dict:
         """Validate search type."""