Task: Code to Text
Input (English): and { only { filter_not_eq { all_rows ; pos ; dnf } } ; eq { hop { filter_not_eq { all_rows ; pos ; dnf } ; year } ; 1989 } } = true
Output (English): select the rows whose pos record does not match to dnf . there is only one such row in the table . the year record of this unqiue row is 1989 .