events

type Emitter interface {
	// Emit fires an event with the given name and payload.
	Emit(EventName, interface{})
	// On registers a listener for the given event name.
	On(EventName, ...Listener)
	// OnMany registers a listener for the given event names.
	ListenEvents(Listener, ...EventName)
}

type EventName string

type Listener func(EventName, interface{}) error

type Logger interface {
	Debugf(format string, args ...interface{})
	Infof(format string, args ...interface{})
	Errorf(format string, args ...interface{})
}