def files
      cli_arguments.each_with_index do |filename, index|
        if Dir.exist?(filename)
          cli_arguments[index] = Dir["#{filename}/**/*.md"]
        end
      end
      cli_arguments.flatten!
      cli_arguments
    end
def files
      cli_arguments.each_with_index do |filename, index|
        if Dir.exist?(filename)
          cli_arguments[index] = Dir["#{filename}/**/*.md"]
        end
      end
      cli_arguments.flatten!
      cli_arguments
    end
List of markdown files from argument list.