<PackageReference Include="System.Reactive" Version="7.0.0-preview.1" />

QueryablePattern<TSource1, TSource2, TSource3, TSource4, TSource5, TSource6, TSource7>

public class QueryablePattern<TSource1, TSource2, TSource3, TSource4, TSource5, TSource6, TSource7> : QueryablePattern
public QueryablePattern<TSource1, TSource2, TSource3, TSource4, TSource5, TSource6, TSource7, TSource8> And<TSource8>(IObservable<TSource8> other)

public QueryablePlan<TResult> Then<TResult>(Expression<Func<TSource1, TSource2, TSource3, TSource4, TSource5, TSource6, TSource7, TResult>> selector)