func cellUnionArea(cu s2.CellUnion) float64 {
var area float64
for _, c := range cu {
cell := s2.CellFromCellID(c)
area += cell.ExactArea()
}
return area
}
func printCells(cu s2.CellUnion) {
for _, c := range cu {
cell := s2.CellFromCellID(c)
area := EarthArea(cell.ExactArea())
r := cell.RectBound()
top := r.Vertex(0).Distance(r.Vertex(1))
side := r.Vertex(1).Distance(r.Vertex(2))
fmt.Printf("Level: %d, Cell: %s, area: %s, boundary: %s x %s\n", c.Level(), c.ToToken(),
area, EarthDistance(top), EarthDistance(side))
}
}