Task: Code to Text
Input (English): and { only { filter_eq { all_rows ; downhill ; - } } ; eq { hop { filter_eq { all_rows ; downhill ; - } ; season } ; 1990 } } = true
Output (English): select the rows whose downhill record is equal to  . there is only one such row in the table . the season record of this unqiue row is 1990 .