CORS in Appwrite Functions - Javascript Fetch CORS Issue

Hello am trying to send a post request to my appwrite functions api server but am getting this error:

Access to fetch at 'https://[url_id].appwrite.global/' from origin 'http://localhost:3005/' has been blocked by CORS policy: Response to preflight request doesn't pass access control check: No 'Access-Control-Allow-Origin' header is present on the requested resource. If an opaque response serves your needs, set the request's mode to 'no-cors' to fetch the resource with CORS disabled.

Your function will need to send back the header to allow your client.

https://developer.mozilla.org/en-US/docs/Web/HTTP/CORS#access-control-allow-origin

and how can i send back the header to the client if am using the appwrite Starter function template

because am trying to set the header like this:

res.setHeader('Access-Control-Allow-Origin', '*');

and am getting this error:
TypeError: res.setHeader is not a function

It would be a parameter to the function: https://github.com/open-runtimes/open-runtimes/blob/a3f20033b642d75096bc9754301e6d1525cebd1e/runtimes/node-20.0/src/server.js#L79