Use RxJS Observable for subscription procedure

import { Observable } from 'rxjs'
import { authedProcedure, createTRPCRouter } from '../../api/trpc'

export const demoRouter = createTRPCRouter({
  fizzBuzz: authedProcedure.subscription(() =>
    new Observable<string>((subscriber) => {
      let i = 1
      const interval = setInterval(() => {
        if (i % 15 === 0) {
          subscriber.next('FizzBuzz')
        } else if (i % 3 === 0) {
          subscriber.next('Fizz')
        } else if (i % 5 === 0) {
          subscriber.next('Buzz')
        } else {
          subscriber.next(String(i))
        }
        i++
      }, 1000)
      return () => clearInterval(interval)
    })
  ),
})