Function install_as 

pub fn install_as(
    store: &Rc<dyn DurableStore>,
    package: &str,
    room: &str,
    checkout: RecordCheckout,
    doc: &mut AutoCommit,
) -> Result<RecordCheckout, TransferError>

install a document that arrived for checkout, including the room’s package-primary record, whose identity the document does not carry.

Errors

A document that is not checkout in room, an occupied id, or storage failure.