cancellable

type Cancellable interface {
	context.Context
	Cancel(err error)            // stop listening and close connection. does not close chan.
	GetContext() context.Context // for interface compatibility (returns underlying Context, not self)
	Wait() error                 // wait for context to be done, return underlying error cause
}

type Chan[T any] interface {
	Cancellable
	UpdatesChan() <-chan T // Returns chan for receiving. choose 1: only use if NOT using Updates()
	Updates() []T          // Collects recent sent-to-chan. choose 1: only use if NOT using UpdatesChan()
	Updates2() []T         // TODO: benchmark this against Updates()
	CloseChan()            // manual, optional: only when no more sending to chan
	Ch() chan<- T          // sender only
}