use warnings;
use strict;
my @a = (1,2,3);
undef @a;
print "a=",@a if @a;

##</code><code>##

@a = (1,2,3);
for my $v (@a) {
  print $v, "\n";
}
print 'Still exist $v? ';
print "No!\n" unless defined $v;