 
 extension DatabaseReader {
     // MARK: - Value Observation Support
-        
+    
+    /// Adding an observation in a read-only database emits only the
+    /// initial value.
     func addReadOnly<Reducer: _ValueReducer>(
         observation: ValueObservation<Reducer>,
         scheduler: ValueObservationScheduler,

        onChange: @escaping (Reducer.Value) -> Void)
        -> TransactionObserver
    {
        if scheduler.impl.fetchOnStart() {
            do {
                try onChange(unsafeReentrantRead(observation.fetchValue))

                onError(error)
            }
        } else {
            asyncRead { [weak observer] dbResult in
                if observer == nil { return }
                let result = dbResult.tryMap(observation.fetchValue)
                scheduler.impl.schedule {
                    if observer == nil { return }
                    do {
                        try onChange(result.get())
                    } catch {
