and { only { filter_eq { all_rows ; of stars ; 15 } } ; eq { hop { filter_eq { all_rows ; of stars ; 15 } ; season } ; 4 - autumn 2008 } } = true
select the rows whose of stars record is equal to 15 . there is only one such row in the table . the season record of this unqiue row is 4  autumn 2008 .