my $c;
my %s;

sub foo {
   my ($x) = @_;;
   $c++;
   $s{\$x}++;

   foo($x-1) if $x;
}

for (1..1000) {
   foo(int(rand(6))+1);
}

print("foo() was called $c times, but only ", scalar(keys(%s)), " sets of lexicals were created.\n");