An accessor that allows for easier FS manipulations
Returns the path relative to the current FS path (usually $server_path/macrocosm)
Initializes the accessor.
Overwrites the file with the provided writer, deleting it if it exists
Overwrites the file, deleting it if it exists
Reads the file data only if file exists, and wraps the result in ConditionalValueCallback
True if Macrocosm has not started before