By requiring a LeafBuilder, you are ensuring that the pipeline is capped with a TailStage as the only way to get a LeafBuilder if by capping with a TailStage or getting a new LeafBuilder from a TailStage
The three fundamental stage types
Facilitates starting a pipeline from a MidStage.
Facilitates starting a pipeline from a MidStage. Can be appended and prepended to build up the pipeline
By requiring a LeafBuilder, you are ensuring that the pipeline is capped with a TailStage as the only way to get a LeafBuilder if by capping with a TailStage or getting a new LeafBuilder from a TailStage
type the pipeline will read and write