<PackageReference Include="System.Reactive" Version="4.1.5" />

Scan<TSource, TAccumulate>

sealed class Scan<TSource, TAccumulate> : Producer<TAccumulate, _<TSource, TAccumulate>>
public Scan(IObservable<TSource> source, TAccumulate seed, Func<TAccumulate, TSource, TAccumulate> accumulator)