// Snippet: OpenFile with more options. Last param is the permission mode
	// Second param is the attributes when opening
	// Use these attributes individually or combined
	// with an OR for second arg of OpenFile()
	// e.g. os.O_CREATE|os.O_APPEND
	// or os.O_CREATE|os.O_TRUNC|os.O_WRONLY
	// os.O_RDONLY // Read only
	// os.O_WRONLY // Write only
	// os.O_RDWR // Read and write
	// os.O_APPEND // Append to end of file
	// os.O_CREATE // Create is none exist
	// os.O_TRUNC // Truncate file when opening

	file, err := os.OpenFile("test.txt", os.O_APPEND, 0666)
	if err != nil {
		log.Fatal(err)
	}
	defer func() { _ = file.Close() }()