Pattern<TSource1, TSource2, TSource3, TSource4>
Represents a join pattern over four observable sequences.
            
                namespace System.Reactive.Joins
{
    public class Pattern<TSource1, TSource2, TSource3, TSource4> : Pattern
    {
        internal IObservable<TSource1> First { get; }
        internal IObservable<TSource2> Second { get; }
        internal IObservable<TSource3> Third { get; }
        internal IObservable<TSource4> Fourth { get; }
        internal Pattern(IObservable<TSource1> first, IObservable<TSource2> second, IObservable<TSource3> third, IObservable<TSource4> fourth)
        {
            First = first;
            Second = second;
            Third = third;
            Fourth = fourth;
        }
        public Pattern<TSource1, TSource2, TSource3, TSource4, TSource5> And<TSource5>(IObservable<TSource5> other)
        {
            if (other == null)
                throw new ArgumentNullException("other");
            return new Pattern<TSource1, TSource2, TSource3, TSource4, TSource5>(this.First, this.Second, this.Third, this.Fourth, other);
        }
        public Plan<TResult> Then<TResult>(Func<TSource1, TSource2, TSource3, TSource4, TResult> selector)
        {
            if (selector == null)
                throw new ArgumentNullException("selector");
            return new Plan<TSource1, TSource2, TSource3, TSource4, TResult>(this, selector);
        }
    }
}