01_langgraph_basicsetup.py

from langgraph.graph import StateGraph, START, END
from typing_extensions import TypedDict
from typing import Literal

class MyState(TypedDict):
    name: str
    value: int

def node_01(MyState: MyState):
    print("node_01 is running")
    MyState["value"] += 1
    MyState["name"] = "Node 01"
    return {
        "name": MyState["name"],
        "value": MyState["value"],
    }
def node_02(MyState: MyState):
    print("node_02 is running")
    MyState["value"] += 1
    MyState["name"] = "Node 02"
    return {
        "name": MyState["name"],
        "value": MyState["value"],
    }

def decision_function(MyState: MyState) -> Literal["node_01", "node_02"]:
    print("decision_function is running")
    if MyState["value"] % 2 == 0:
        return "node_01"
    else:
        return "node_02"

builder = StateGraph(MyState)


builder.add_node("node_01", node_01)
builder.add_node("node_02", node_02)

builder.add_edge(START, "node_01")
builder.add_conditional_edges("node_01", decision_function)
builder.add_edge("node_01", END)
builder.add_edge("node_02", END)


graph = builder.compile()

output = graph.invoke({"name": "Ali Hassan", "value": 18})

print("Final output:", output)