and { only { filter_eq { all_rows ; 1 usd = ; 1 } } ; eq { hop { filter_eq { all_rows ; 1 usd = ; 1 } ; country } ; ecuador } } = true
select the rows whose 1 usd = record is equal to 1 . there is only one such row in the table . the country record of this unqiue row is ecuador .