How to manually invoke server functions?

export const increment = async (gameId: string) => {
  "use server";
  const event = getRequestEvent()!;
  const cloudflare = event.nativeEvent.context.cloudflare;

  // We're in the worker not the durable object
  if (!cloudflare.durable) {
    const binding = cloudflare.env.GAME;
    const id = binding.idFromName(gameId);

    return (await binding.get(id).fetch(event.request)) as number;
  }

  let value: number = (await cloudflare.context.storage.get("counter")) || 0;

  value += 1;
  await cloudflare.context.storage.put("counter", value);

  return value;
};