code: func (cur *seriesCursor) Next() (*SeriesCursorRow, error) {
  	for {
  		// Read series keys for next measurement if no more keys remaining.
  		// Exit if there are no measurements remaining.
  		if cur.ofs == len(cur.keys) {
  			m, err := cur.mitr.Next()
  			if err != nil {
  				return nil, err
  			} else if m == nil {
  				return nil, nil
  			}
  
  			if err := cur.readSeriesKeys(m); err != nil {
  				return nil, err
  			}
  			continue
  		}
  
  		cur.row.Name, cur.row.Tags = tsdb.ParseSeriesKey(cur.keys[cur.ofs])
  		cur.ofs++
  		return &cur.row, nil
  	}
  }
docs: // Next emits the next point in the iterator.