shuttle
Creates a new Draft whose first stage is a DraftStage.Source identified by sourceOpId.
The source stage represents named data living on peers — a collection, a named view, or any operation that produces elements for downstream stages. Chain Draft.map, Draft.filter, and Draft.embroider on the returned Draft to build up the full pipeline.
No op is invoked. Only the name is recorded.
Return
a single-stage Draft ready to extend with transforms.
Parameters
sourceOpId
the symbolic name of the source operation.