$x = 10;
*y = *x;
$z = \$x;

{
    print "\$x = $x, \$y = $y, \$\$z = $$z \n";
    $savex = $x;
    print "\$x = $x, \$y = $y, \$\$z = $$z \n";
    $x = 20;
    print "\$x = $x, \$y = $y, \$\$z = $$z \n";
    $x = $savex;
}