def validate(result)
      if result.ntuples == 0
        raise NotFound
      elsif result.ntuples > 1
        raise TooManyChoices
      end
    end
def validate(result)
      if result.ntuples == 0
        raise NotFound
      elsif result.ntuples > 1
        raise TooManyChoices
      end
    end
Checks the number of values returned when looking up meta info about
 the procedure.
 @see #load
 @see #info_sql