Register a subscriber that will be notified with a [!:Changed<T>] message when the value of the given Key is changed. Current value is also sent as a [!:Changed<T>] message to a new subscriber. Subscribers will be notified periodically with the configured `notify-subscribers-interval`, and it is also possible to send an explicit `FlushChanges` message to the Replicator to notify the subscribers immediately. The subscriber will automatically be unregistered if it is terminated. If the key is deleted the subscriber is notified with a [!:DataDeleted<T>] message.

[SerializableAttribute]
public sealed class Subscribe : IReplicatorMessage, 
	IEquatable<Subscribe>

[<SealedAttribute>]
[<SerializableAttribute>]
type Subscribe =  
    class
        interface IReplicatorMessage
        interface IEquatable<Subscribe>
    end