text: #include <unistd.h>
  
  int	rotone(char letter)
  {
  	int	index;
  
  	index = letter;
  	if (letter >= 'a' && letter <= 'z')
  		index = (letter - 'a' + 1) % 26 + 'a';
  	else if (letter >= 'A' && letter <= 'Z')
  		index = (letter - 'A' + 1) % 26 + 'A';
  	return (index);
  }
  
  int	main(int argc, char *argv[])
  {
  	int	i;
  	int	value;
  
  	i = 0;
  	if (argc == 2)
  	{
  		while (argv[1][i])
  		{
  			value = rotone(argv[1][i]);
  			write(1, &value, 1);
  			i++;
  		}
  	}
  	write(1, "\n", 1);
  	return (0);
  }
  