Returns true if the replica already exists / has been initialized. Returns false otherwise.
Returns true if PATH is a file or directory in this replica's directory structure
Walks through all changesets from $after to $until, calling $callback on each.
If no $until is specified, the latest changeset is assumed.
Returns the contents of the given file in this replica's userdata directory.
undef if the file does not exist.
Writes the given string to the given file in this replica's userdata directory.