my $text = "Hello world\n";
my $var  = 'Hello world\n';

print $text;
print $var;

##</code><code>##

my $text = "Hello world\n";
print "$text";
print '$text';

##</code><code>##

my %hash = ( This => 10,
             That => 20
            );

##</code><code>##

my %hash = ( 'This' , 10,
             'That' , 20
           );