distinct operator variation

[parloti]

I need a variation of the distinct operator, whose internal HashSet is populated by another one observable instead of by the keySelector function.

distinctWith<TValue, TKey> (
   distinct$: Observable<TKey> /* Emissions from this observable will be added to the HashSet */,
   keySelector?: (value: TValue) => TKey /* Just like in distinct */,
   flushes?: Observable <unknown> /* Just like in distinct */
)

I'm already testing my own implementation for rxjs 6, like this DistinctWith. But I want to migrate to rxjs 7, and my code is no longer compatible.

I would also be happy with a combination of existing operators.

Thanks in advance