iterator

type Interface[K, V any] interface {
	// Next returns the next key/value pair, where the key is a slice index, map key, document number, etc,
	// and the value is the slice or map value, next document, etc.
	// Returned error could be (possibly wrapped) ErrIteratorDone or some fatal error.
	Next() (K, V, error)

	// Close indicates that the iterator will no longer be used.
	// If Close is called, future calls to Next might panic.
	// Close must be concurrency-safe and may be called multiple times.
	// All calls after the first will have no effect.
	Close()
}