 
     /// Adds or updates an existing object into the Realm.
     ///
+    /// - Warning: This method is not thread safe for now. It is not better to pass object directly.
+    ///  If you want to use this method safely, you should call `realm.run(io:)` in a same thread, or 
+    ///  use with `flatMap`.
     /// - Parameter object: The object to be added to this Realm.
     /// - Parameter update: If `true`, the Realm will try to find an existing copy of the object
     ///     (with the same primary key), and update it. Otherwise, the object will be added.


    /// Deletes zero or more objects from the Realm.
    ///
    /// - Parameter objects: A list of objects to delete.
    /// - Returns: `Write` operation
    public static func delete<T: Object>(_ objects: List<T>) -> RealmWrite<Void> {


    /// Adds or updates all the objects in a collection into the Realm.
    ///
    /// - Warning: This method is not thread safe for now. It is not better to pass object directly.
    ///  If you want to use this method safely, you should call `realm.run(io:)` in a same thread, or 
    ///  use with `flatMap`.
    /// - Parameter objects: A sequence which contains objects to be added to the Realm.
    /// - Parameter update: If `true`, objects that are already in the Realm will be updated instead of added anew.
    /// - Returns: `Write` operation
