SUSPENSE is a special symbol that can be emitted from observables to let the React hook know that there is a value on its way, and that we want to leverage React Suspense while we are waiting for that value.

const SUSPENSE: unique symbol;


import { concat, switchMap } from 'rxjs/operators'
import { SUSPENSE } from '@react-rxjs/core'
const story$ = selectedStoryId$.pipe(
switchMap((id) => concat(SUSPENSE, getStory$(id))),

See also