Scan<TSource, TAccumulate>
                
                    sealed class Scan<
TSource, 
TAccumulate> : 
Producer<
TAccumulate, 
_<
TSource, 
TAccumulate>>
                
 
                
                
                
public Scan(
IObservable<
TSource> 
source, 
TAccumulate seed, 
Func<
TAccumulate, 
TSource, 
TAccumulate> 
accumulator)