namespace System.Reactive.Operators
    module IObservableOps =
        open System
        val Filtered : IObservable<Option<'a>> -> IObservable<'a> //Implemented
        val Disjoin : IObservable<'a> -> IObservable<'b> -> IObservable<Choice<'a,'b>>
        val DisjoinBy : (Choice<'a,'b> -> Option<'c>) ->  IObservable<'a> -> IObservable<'b> -> IObservable<'c>
        val DisjointScan : ('s -> Choice<'a,'b> -> 's * Option<'c>) ->  IObservable<'a> -> IObservable<'b> -> IObservable<'c>
        val Conjoin : IObservable<'a> -> IObservable<'b> -> IObservable<'a * 'b> //Implemented by Rx, called "And"
        val ConjoinedScan :  ('a -> 'b -> Option<'c>) -> IObservable<'a> -> IObservable<'b> -> IObservable<'c>
        val ConjoinByAndScan : ('s -> 'a -> 'b -> 's * Option<'c>) -> IObservable<'a> -> IObservable<'b> -> IObservable<'c>
        val FilterMap : ('a -> Option<'b>) -> IObservable<'a> -> IObservable<'b> //Implemented
        val FilterMapScan : ('s -> 'a -> 's * Option<'b>) -> IObservable<'a> -> IObservable<'b>