geohash.go
func EncodeIntWithPrecision(lat, lng float64, bits uint) uint64 {
	hash := EncodeInt(lat, lng)
	return hash >> (64 - bits)
}
func EncodeIntWithPrecision(lat, lng float64, bits uint) uint64 {
	hash := EncodeInt(lat, lng)
	return hash >> (64 - bits)
}
// EncodeIntWithPrecision encodes the point (lat, lng) to an integer with the
// specified number of bits.