medium-address-epic.ts

const findAddresses = actions$ => actions$.pipe(
  ofType(actions.FIND_ADDRESSES),
  map(action => action.partialAddress),
  debounceTime(400),
  distinctUntilChanged(),
  switchMap(partialAddress => this.backend
    .findAddresses(partialAddress)
    .pipe(
      map(results => actions.findAddressesFulfilled(results)),
      catchError(error => of(actions.findAddressesRejected(error)))
    )
  )
);