func s2PolygonToGeometry(poly s2.Polygon) *geojson.Polygon {
// Don't want nil rings for coordinates.
rings := [][]geojson.Coordinate{}
for i := 0; i < poly.NumLoops(); i++ {
loop := poly.Loop(i)
var ring []geojson.Coordinate
for j := 0; j <= loop.NumVertices(); j++ {
ll := s2.LatLngFromPoint(*loop.Vertex(j))
ring = append(ring, geojson.Coordinate{ll.Lng.Degrees(), ll.Lat.Degrees()})
}
rings = append(rings, ring)
}
return &geojson.Polygon{Typ: "Polygon", Coordinates: rings}
}
