question: private ExchangeRate directLookup ( final Currency source , final Currency target , final Date date ) { if ( System . getProperty ( "EXPERIMENTAL" ) == null ) throw new UnsupportedOperationException ( "Work in progress" ) ; ExchangeRate rate = null ; QL . require ( ( ( rate = fetch ( source , target , date ) ) != null ) , "no direct conversion available" ) ; return rate ; }
target:  Fetches a exchange rate from the repository.