Use iron session with create-t3-app

.ts

export const trpc = createTRPCNext({
  config({ ctx }) {
    return {
      ...
      /**
       * @link https://trpc.io/docs/links
       */
      links: [
        ...,
        httpLink({
          /*
           * Set custom request headers on every request from tRPC
           * @link https://trpc.io/docs/ssr
           */
          headers() {
            if (ctx?.req) {
              // To use SSR properly, you need to forward the client's headers to the server
              // This is so you can pass through things like cookies when we're server-side rendering

              // If you're using Node 18, omit the "connection" header
              const { connection: _connection, ...headers } = ctx.req.headers
              return {
                ...headers,
                // Optional: inform server that it's an SSR request
                'x-ssr': '1',
              }
            }
          },
        }),
      ],
    }
  },
})

i also use create-t3-app, but there isn't any createTRPCNext initialization from the default create-t3-app setup. where i must put this file?