c:\@Work\Perl\monks>perl -wMstrict -le
"my $x;
 ;;
 S('A');
 ;;
 $x = 'foo';
 ;;
 S('B');
 ;;
 sub S { print qq{$_[0]: x is }, defined $x ? qq{'$x'} : 'undefined'; }
"
A: x is undefined
B: x is 'foo'