```ts
import * as z from "zod";

import {
  END,
  MemorySaver,
  START,
  StateGraph,
  StateSchema,
  task,
} from "@langchain/langgraph";
import type { GraphNode } from "@langchain/langgraph";

const State = new StateSchema({
  urls: z.array(z.string()),
  results: z.array(z.string()).optional(),
});

const makeRequest = task("makeRequest", async (url: string) => {
  const response = await fetch(url); // [!code highlight]
  const text = await response.text();
  return text.slice(0, 100);
});

const callApi: GraphNode<typeof State> = async (state) => {
  const pending = state.urls.map((url) => makeRequest(url)); // [!code highlight]
  const results = await Promise.all(pending);
  return { results };
};

const builder = new StateGraph(State)
  .addNode("callApi", callApi)
  .addEdge(START, "callApi")
  .addEdge("callApi", END);

const checkpointer = new MemorySaver();
const graph = builder.compile({ checkpointer });

const threadId = crypto.randomUUID();
const config = { configurable: { thread_id: threadId } };

await graph.invoke({ urls: ["https://www.example.com"] }, config);
```