Updated some more content

Lang_Graph.html

@@ -138,7 +138,32 @@
 
     </p>
    
-    
+       <p>
+        Going little further into the topic. Use an annotated list to preserve the history
+        <pre>
+            class State(TypedDict):
+                value: str
+                history: Annotated[list[str], operator.add]
+
+            def First_Node(state: State):
+                    print("I am from first Node")
+                    return {"value": "First Node done", "history": ["First Node Activated"]}
+
+            def Second_Node(state: State):
+                    print("I am from Second Node")
+                    return {"value": "Second Node done", "history": ["Second Node Activated"]}
+
+            ...
+            final_response = graph.invoke({"value": [], "history": ["User initiated session"]})
+        </pre>
+        You would see an output like this. <br>
+        the final value is : {'value': 'Second Node done', 'history': ['User initiated session', 'First Node Activated', 'Second Node Activated']}
+        Try running the nodes in parallel by trying something like this.<br>
+        <pre>
+            workflow.add_edge(START, "Node_A")
+            workflow.add_edge(START, "Node_B")
+        </pre>
+   </p>
     <h3>Detailed article coming soon ..</h3>
      
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