$foo = 5;
   sub do_something { print $foo, $/; }
   sub main
   {
      do_something();
      {
        local $foo = 6;
        do_something();
      }
      do_something();
   }
   main();

##</code><code>##

      {
        my $unnamed_backup_of_old_value_of_foo = $foo;
        $foo = 6;
        do_something();
        $foo = $unnamed_backup_of_old_value_of_foo;
      }