class IO
  def hello_world
    path = "fileio.txt"
    writeFile(path, "hello") do |file|
      file = File.open(path, "a") do
        write(file, "\nworld") do
          close(file) do
            data = read(path) do
              puts data.last
            end
          end
        end
      end
    end
  end
end

IO.new.hello_world