code: func ColumnUnmarshallerWithTimestamp(format Format, timestampFormat string) RecordUnmarshaller {
  	return func(text string) (pilosa.Record, error) {
  		var err error
  		column := pilosa.Column{}
  		parts := strings.Split(text, ",")
  		if len(parts) < 2 {
  			return nil, errors.New("Invalid CSV line")
  		}
  
  		hasRowKey := format == RowKeyColumnID || format == RowKeyColumnKey
  		hasColumnKey := format == RowIDColumnKey || format == RowKeyColumnKey
  
  		if hasRowKey {
  			column.RowKey = parts[0]
  		} else {
  			column.RowID, err = strconv.ParseUint(parts[0], 10, 64)
  			if err != nil {
  				return nil, errors.New("Invalid row ID")
  			}
  		}
  
  		if hasColumnKey {
  			column.ColumnKey = parts[1]
  		} else {
  			column.ColumnID, err = strconv.ParseUint(parts[1], 10, 64)
  			if err != nil {
  				return nil, errors.New("Invalid column ID")
  			}
  		}
  
  		timestamp := 0
  		if len(parts) == 3 {
  			if timestampFormat == "" {
  				timestamp, err = strconv.Atoi(parts[2])
  				if err != nil {
  					return nil, err
  				}
  			} else {
  				t, err := time.Parse(timestampFormat, parts[2])
  				if err != nil {
  					return nil, err
  				}
  				timestamp = int(t.Unix())
  			}
  		}
  		column.Timestamp = int64(timestamp)
  
  		return column, nil
  	}
  }
docs: // ColumnUnmarshallerWithTimestamp creates a RecordUnmarshaller for importing columns with the given format and timestamp format.