code: func (c *Client) ReadingsByCreationTime(start, end int64, limit int) (readings []contract.Reading, err error) {
  	conn := c.Pool.Get()
  	defer conn.Close()
  
  	if limit == 0 {
  		return readings, nil
  	}
  
  	objects, err := getObjectsByScore(conn, db.ReadingsCollection+":created", start, end, limit)
  	if err != nil {
  		return readings, err
  	}
  
  	readings = make([]contract.Reading, len(objects))
  	for i, in := range objects {
  		err = unmarshalObject(in, &readings[i])
  		if err != nil {
  			return readings, err
  		}
  	}
  
  	return readings, nil
  }
docs: // Return a list of readings whos created time is between the start and end times