code: func EncodeWithPrecision(lat, lng float64, chars uint) string {
  	bits := 5 * chars
  	inthash := EncodeIntWithPrecision(lat, lng, bits)
  	enc := base32encoding.Encode(inthash)
  	return enc[12-chars:]
  }
docs: // EncodeWithPrecision encodes the point (lat, lng) as a string geohash with
  // the specified number of characters of precision (max 12).