# File lib/yell/formatter.rb, line 136
      def call( message )
        case
        when mod = @repository[message.class] || @repository[message.class.to_s]
          mod.call(message)
        when message.is_a?(Array)
          message.map { |m| call(m) }.join(" ")
        when message.is_a?(Hash)
          message.map { |k, v| "#{k}: #{v}" }.join(", ")
        when message.is_a?(Exception)
          backtrace = message.backtrace ? "\n\t#{message.backtrace.join("\n\t")}" : ""
          sprintf("%s: %s%s", message.class, message.message, backtrace)
        else
          message
        end
      end