func NewExpiringClusteringIndex(expiration Minutes) *ClusteringIndex {
	index := &ClusteringIndex{}
	index.streetLevel = NewExpiringPointsIndex(Km(0.5), expiration)
	index.cityLevel = NewExpiringCountIndex(Km(10), expiration)
	index.worldLevel = NewExpiringCountIndex(Km(500), expiration)

	return index
}
func NewExpiringClusteringIndex(expiration Minutes) *ClusteringIndex {
	index := &ClusteringIndex{}
	index.streetLevel = NewExpiringPointsIndex(Km(0.5), expiration)
	index.cityLevel = NewExpiringCountIndex(Km(10), expiration)
	index.worldLevel = NewExpiringCountIndex(Km(500), expiration)

	return index
}
func NewExpiringClusteringIndex ( expiration Minutes ) * ClusteringIndex { index := & ClusteringIndex { } index . streetLevel = NewExpiringPointsIndex ( Km ( 0.5 ) , expiration ) index . cityLevel = NewExpiringCountIndex ( Km ( 10 ) , expiration ) index . worldLevel = NewExpiringCountIndex ( Km ( 500 ) , expiration ) return index }
// NewExpiringClusteringIndex creates index that clusters the points at three levels with cell size 0.5, 5 and 500km and
// expires them after expiration minutes.
NewExpiringClusteringIndex creates index that clusters the points at three levels with cell size 0 . 5 5 and 500km and expires them after expiration minutes .