    # File lib/plugins/history.rb, line 44
      def self.save_history
        filename = File.expand_path(config.plugins.history.filename)
        keys = config.plugins.history.keys
        history = { }
        keys.each do |key|
          history[key] = public_storage[key]
        end
        max_of_history = config.plugins.history.max_of_history
        history[:history] = Readline::HISTORY.to_a.reverse.uniq.reverse
        if history[:history].size > max_of_history
          history[:history] = history[:history][-max_of_history..-1]
        end

        File.open(filename, 'w') do |f|
          f.write Zlib::Deflate.deflate(Marshal.dump(history))
        end
        puts "history saved(#{File.size(filename)/1000}kb)"
      end