# File lib/logging/appenders/buffering.rb, line 53
    def immediate_at=( level )
      @immediate ||= []
      @immediate.clear

      # get the immediate levels -- no buffering occurs at these levels, and
      # a log message is written to the logging destination immediately
      immediate_at =
        case level
        when String; level.split(',').map {|x| x.strip}
        when Array; level
        else Array(level) end
      
      immediate_at.each do |lvl|
        num = ::Logging.level_num(lvl)
        next if num.nil?
        @immediate[num] = true
      end
    end