Function init_scoped 

pub fn init_scoped(
    doc: &mut AutoCommit,
    id: &RecordId,
    kind: &RecordKind,
    home: &str,
    room: Option<&str>,
) -> bool

Bind a record document to room. Unlike the historical init, this never rewrites an existing identity or room: accepting a document stamped for another room would turn a matching record id into a cross-room alias. A room-less legacy document may be adopted exactly once after its identity has been checked.