diff --git a/lightrag/base.py b/lightrag/base.py
index 8e6a212d..b1fe50a2 100644
--- a/lightrag/base.py
+++ b/lightrag/base.py
@@ -95,7 +95,7 @@ class StorageNameSpace:
 @dataclass
 class BaseVectorStorage(StorageNameSpace):
     embedding_func: EmbeddingFunc
-    meta_fields: set = field(default_factory=set)
+    meta_fields: set[str] = field(default_factory=set)
 
     async def query(self, query: str, top_k: int) -> list[dict[str, Any]]:
         raise NotImplementedError
@@ -130,50 +130,64 @@ class BaseKVStorage(StorageNameSpace):
 
 @dataclass
 class BaseGraphStorage(StorageNameSpace):
-    embedding_func: EmbeddingFunc = None
-
+    embedding_func: EmbeddingFunc | None = None
+    """Check if a node exists in the graph."""
     async def has_node(self, node_id: str) -> bool:
         raise NotImplementedError
 
+    """Check if an edge exists in the graph."""
     async def has_edge(self, source_node_id: str, target_node_id: str) -> bool:
         raise NotImplementedError
 
+    """Get the degree of a node."""
     async def node_degree(self, node_id: str) -> int:
         raise NotImplementedError
 
+    """Get the degree of an edge."""
     async def edge_degree(self, src_id: str, tgt_id: str) -> int:
         raise NotImplementedError
 
-    async def get_node(self, node_id: str) -> Union[dict, None]:
+    """Get a node by its id."""
+    async def get_node(self, node_id: str) -> Union[dict[str, str], None]:
         raise NotImplementedError
 
+    """Get an edge by its source and target node ids."""
     async def get_edge(
         self, source_node_id: str, target_node_id: str
-    ) -> Union[dict, None]:
+    ) -> Union[dict[str, str], None]:
         raise NotImplementedError
 
+    """Get all edges connected to a node."""
     async def get_node_edges(
         self, source_node_id: str
     ) -> Union[list[tuple[str, str]], None]:
         raise NotImplementedError
 
-    async def upsert_node(self, node_id: str, node_data: dict[str, str]):
+    """Upsert a node into the graph."""
+    async def upsert_node(self, node_id: str, node_data: dict[str, str]) -> None:
         raise NotImplementedError
 
+    """Upsert an edge into the graph."""
     async def upsert_edge(
-        self, source_node_id: str, target_node_id: str, edge_data: dict[str, str]
-    ):
+        self, source_node_id: str,
+        target_node_id: str, 
+        edge_data: dict[str, str]
+    ) -> None:
         raise NotImplementedError
 
-    async def delete_node(self, node_id: str):
+    """Delete a node from the graph."""
+    async def delete_node(self, node_id: str) -> None:
         raise NotImplementedError
 
-    async def embed_nodes(self, algorithm: str) -> tuple[np.ndarray, list[str]]:
+    """Embed nodes using an algorithm."""
+    async def embed_nodes(self, algorithm: str) -> tuple[np.ndarray[Any, Any], list[str]]:
         raise NotImplementedError("Node embedding is not used in lightrag.")
 
+    """Get all labels in the graph."""
     async def get_all_labels(self) -> list[str]:
         raise NotImplementedError
 
+    """Get a knowledge graph of a node."""
     async def get_knowledge_graph(
         self, node_label: str, max_depth: int = 5
     ) -> KnowledgeGraph:
diff --git a/lightrag/lightrag.py b/lightrag/lightrag.py
index 15bb6cc2..593b5734 100644
--- a/lightrag/lightrag.py
+++ b/lightrag/lightrag.py
@@ -6,7 +6,7 @@ import configparser
 from dataclasses import asdict, dataclass, field
 from datetime import datetime
 from functools import partial
-from typing import Any, Callable, Optional, Union, cast
+from typing import Any, AsyncIterator, Callable, Iterator, Optional, Union, cast
 
 from .base import (
     BaseGraphStorage,
@@ -983,7 +983,7 @@ class LightRAG:
 
     def query(
         self, query: str, param: QueryParam = QueryParam(), prompt: str | None = None
-    ) -> str:
+    ) -> str | Iterator[str]:
         """
         Perform a sync query.
 
@@ -1003,7 +1003,7 @@ class LightRAG:
         query: str,
         param: QueryParam = QueryParam(),
         prompt: str | None = None,
-    ) -> str:
+    ) -> str | AsyncIterator[str]:
         """
         Perform a async query.
 
@@ -1081,7 +1081,10 @@ class LightRAG:
         return response
 
     def query_with_separate_keyword_extraction(
-        self, query: str, prompt: str, param: QueryParam = QueryParam()
+        self, 
+        query: str, 
+        prompt: str, 
+        param: QueryParam = QueryParam()
     ):
         """
         1. Extract keywords from the 'query' using new function in operate.py.
@@ -1093,7 +1096,10 @@ class LightRAG:
         )
 
     async def aquery_with_separate_keyword_extraction(
-        self, query: str, prompt: str, param: QueryParam = QueryParam()
+        self, 
+        query: str, 
+        prompt: str, 
+        param: QueryParam = QueryParam()
     ):
         """
         1. Calls extract_keywords_only to get HL/LL keywords from 'query'.