NewBroker creates a new pub/sub broker.

NewBrokerEx creates a new pub/sub broker, with a hook to be called when a new subscriber is registered.

NewContextSubscription creates a subscription that cancels the context when closed.

Broker is a pub/sub broker instance.

Subscription is a Broker subscription instance.

ClosableSubscription is an interface for a subscription that can be closed.

OnSubscribeHook is the on-subscribe callback hook prototype.