@x=(\$_,\$_);
$_=10;
print "\$x[$_] = ${$x[$_]}\n" for 0..$#x;
$_=20;
print "\$x[$_] = ${$x[$_]}\n" for 0..$#x;
__DATA__
$x[0] = 10
$x[1] = 10
$x[0] = 20
$x[1] = 20