diff --git a/Exercises/Exercise_Graph4.ipynb b/Exercises/Exercise_Graph4.ipynb
index babdd31..7a6a976 100644
--- a/Exercises/Exercise_Graph4.ipynb
+++ b/Exercises/Exercise_Graph4.ipynb
@@ -48,7 +48,7 @@
     "    state[\"finalNumber\"] = state[\"number1\"] - state[\"number2\"]\n",
     "    return state\n",
     "\n",
-    "def decide_next_node(state:AgentState) -> AgentState:\n",
+    "def decide_next_node(state:AgentState) -> str:\n",
     "    \"\"\"This node will select the next phase\"\"\"\n",
     "    if state[\"operation\"] == \"+\":\n",
     "        return \"addition_operation\"\n",
@@ -73,7 +73,7 @@
     "    print(state[\"finalNumber2\"])\n",
     "    return state\n",
     "\n",
-    "def decide_next_node1(state:AgentState) -> AgentState:\n",
+    "def decide_next_node1(state:AgentState) -> str:\n",
     "    \"\"\"This node will select the next phase\"\"\"\n",
     "    if state[\"operation2\"] == \"+\":\n",
     "        print(\"ADD1\")\n",