Function retire 

pub fn retire(
    store: &Rc<dyn DurableStore>,
    package: &str,
    workspace: &str,
    origin: &Origin,
    why: &Retirement,
) -> Result<Option<Landing>, TransferError>

Stamp origin in workspace as retired: one last change in its own history, after which it is never opened as a live document again. No write, and no Landing, for one already retired.

Errors

TransferError::Busy while an app still holds the document, a missing or foreign document, or storage failure.