Revert "removed get_knowledge_graph"

lightrag/kg/tidb_impl.py

@@ -5,6 +5,8 @@ from typing import Any, Union, final
 
 import numpy as np
 
+from lightrag.types import KnowledgeGraph
+
 
 from ..base import BaseGraphStorage, BaseKVStorage, BaseVectorStorage
 from ..namespace import NameSpace, is_namespace
@@ -558,6 +560,11 @@ class TiDBGraphStorage(BaseGraphStorage):
     async def delete_node(self, node_id: str) -> None:
         raise NotImplementedError
 
+    async def get_knowledge_graph(
+        self, node_label: str, max_depth: int = 5
+    ) -> KnowledgeGraph:
+        raise NotImplementedError
+
 
 N_T = {
     NameSpace.KV_STORE_FULL_DOCS: "LIGHTRAG_DOC_FULL",