code: func (points *PointsIndex) Range(topLeft Point, bottomRight Point) []Point {
  	entries := points.index.Range(topLeft, bottomRight)
  	accept := func(point Point) bool {
  		return between(point.Lat(), bottomRight.Lat(), topLeft.Lat()) &&
  			between(point.Lon(), topLeft.Lon(), bottomRight.Lon())
  	}
  
  	return getPoints(entries, accept)
  }
docs: // Range returns the points within the range defined by top left and bottom right.