use strict;
use warnings;

my @L = ('1', '0', '');

while (@L) {
	if (my $x = shift @L) {
		print "\$x is true: <$x>\n";
	} elsif (length $x) {
		print "\$x is false: <$x>\n";
	} else {
		print "\$x is still false<$x>\n";
	}
	# print "$x\n";	# yields a strict error when uncommented
}