use strict;
use warnings;

sub testUnless {
    my $v = 'Navidson';
    unless ( $v ) {}; # returns $v
}
sub testIfNot {
    my $v = 'Holloway';
    if ( ! $v ) {};   # returns ! $v
}
sub testIf {
    my $v = 0;
    if ( $v ) {}      # returns $v
}
sub testNothing {
    my $v = 'kyle';
    if ( $v ) {}      # returns nothing
}

printf "testUnless  -> [%s]\n", testUnless();
printf "testIfNot   -> [%s]\n", testIfNot();
printf "testIf      -> [%s]\n", testIf();
printf "testNothing -> [%s]\n", testNothing();
__END__
testUnless  -> [Navidson]
testIfNot   -> []
testIf      -> [0]
Use of uninitialized value in printf ...
testNothing -> []