app.use((next) =>
  (c) => {
    c.set("Name", "Mu Shan");
    return next(c);
  }
);

app.get("/", (c) => {
  return `Hello ${c.get("Name")}`;
});

// Define `CustomContext`
class CustomContext extends Context {
  constructor(c: Context) {
    super(c);
  }

  hello() {
    this.string("Hello World!");
  }
}

// Replace the original `Context`
app.pre((next) =>
  (c) => {
    const cc = new CustomContext(c);
    return next(cc);
  }
);

app.get("/", (c) => {
  const cc: CustomContext = c.customContext!;
  cc.hello();
});

app.start({ port: 8080 });