#  perl -e 'use Time::Piece; $x = localtime; $y = localtime() - $x; print "$y\n";  '
0


#  perl -e 'use Time::Piece; $x = localtime; $y = (localtime) - $x; print "$y\n";  '
0


# perl -e 'use Time::Piece; $x = localtime; $y = localtime - $x; print "$y\n";  '
Thu Jan  1 01:00:00 1970