xzdiff --version (return code: 0)
xzdiff (XZ Utils) 5.1.0alpha
xzdiff --help (return code: 0)
Usage: xzdiff [OPTION]... FILE1 [FILE2] Compare FILE1 to FILE2, using their uncompressed contents if they are compressed. If FILE2 is omitted, then the files compared are FILE1 and FILE1 from which the compression format suffix has been stripped. Do comparisons like 'diff' does. OPTIONs are the same as for 'diff'. Report bugs to <firstname.lastname@example.org>.