compilation warning

untitled.c:70:9: warning: enumeration value 'OK' not handled in switch
      [-Wswitch]
        switch(err) {
This situation can never occur because we have this code:

````c
		if((err = process_file(argv[i])) != OK) {
			print_error(argv[i], err);
		}
````

Instead, if this warning really bothers you, just put a `default: return;` here instead