<PackageReference Include="System.Reactive" Version="4.1.3" />

QueryablePattern<TSource1, TSource2>

public class QueryablePattern<TSource1, TSource2> : QueryablePattern
Represents a join pattern over two observable sequences.
public QueryablePattern<TSource1, TSource2, TSource3> And<TSource3>(IObservable<TSource3> other)

Creates a pattern that matches when all three observable sequences have an available element.

public QueryablePlan<TResult> Then<TResult>(Expression<Func<TSource1, TSource2, TResult>> selector)

Matches when all observable sequences have an available element and projects the elements by invoking the selector function.