rate

type Limiter interface {
	// New returns a new limiter that is subordinate to this limiter, meaning that its cap rate is also capped by its
	// parent.
	New(capacity int) Limiter

	// Cap returns the capacity per time period.
	Cap(applyParentCaps bool) int

	// SetCap sets the capacity.
	SetCap(capacity int)

	// LastUsed returns the capacity used in the last time period.
	LastUsed() int

	// Use returns a channel that will return nil when the request is successful, or an error if the request cannot be
	// fulfilled.
	Use(amount int) <-chan error

	// Closed returns true if the limiter is closed.
	Closed() bool

	// Close this limiter and any children it may have.
	Close()
}