my ($x, $y, $z) = ('', '', '');
($x, $y, $z) = split(',', $_);
##</code><code>##

$_ = 'a,b';
my ($x, $y, $z) = ('', '', '');
($x, $y, $z) = split(',', $_);
print(defined($z)?'defined':'undefined', "\n");
# prints undefined.

##</code><code>##

my ($x, $y, $z) = map { defined($_)?$_:'' } (split(',', $_))[0..2];