In the previous chapter, we saw how to create sequences other than simply implementing the IObservable interface by creating our custom observables using the Subject class that gives us an initial implementation which is useful in a lot of cases, thus reducing the bootstrap time when programming in a reactive way.
We can create a new observable subject simply with the new keyword of the C# programming language. The same happens in regard to customized observable sequences (by implementing the IObservable interface). Other than this, we can create generic observable sequences with the factory methods available within the observable helper class that give us the ability to create sequences from the scratch without having to create custom classes, or by other values or other CLR objects, such as events and so on. These sequences are only observable sequences; they are not subjects and they are not observers.
A lot of the following factory methods will simply translate...