<PackageReference Include="System.Reactive" Version="4.3.1" />

Pattern<TSource1, TSource2, TSource3, TSource4>

public class Pattern<TSource1, TSource2, TSource3, TSource4> : Pattern
Represents a join pattern over four observable sequences.
public Pattern<TSource1, TSource2, TSource3, TSource4, TSource5> And<TSource5>(IObservable<TSource5> other)

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

public Plan<TResult> Then<TResult>(Func<TSource1, TSource2, TSource3, TSource4, TResult> selector)

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