%title%

    # File /home/cepheus/projects/prep/log4r-1.0.1/src/log4r/outputter/outputter.rb, line 44
        def only_at(*levels)
          raise ArgumentError, "Gimme some levels!", caller if levels.empty?
          raise ArgumentError, "Can't log only_at ALL", caller if levels.include? ALL
          levels.each {|level| Log4rTools.validate_level(level)}
          @level = levels.sort.first
          OutputterFactory.create_methods self, levels
          Logger.log_internal {
            "Outputter '#{@name}' writes only on " +\
            levels.collect{|l| LNAMES[l]}.join(", ")
          }
        end