eq { diff { hop { filter_eq { all_rows ; school ; leo } ; year joined } ; hop { filter_eq { all_rows ; school ; south adams } ; year joined } } ; -20 years } = true
select the rows whose school record fuzzily matches to leo . take the year joined record of this row . select the rows whose school record fuzzily matches to south adams . take the year joined record of this row . the second record is 20 years larger than the first record .