Function author_writer 

pub fn author_writer(record_writer: &ActorId, author: &str) -> ActorId

The actor author’s mount edits a record as, when the record’s own writer is record_writer and the host asked for per-author writers (crate::application::HostContext::write_as_author). Mounts of one profile and device share a record’s document and so its writer; this keeps each author’s edits apart in history. It is unique wherever the record’s writer is, and the same after a reopen, so history names the same author again.