<?hh
function main() {
  $y = 20;
  var_dump($y += 10);

  $var = 'x';
  $x = 20;
  var_dump($$var += 10);

  $_SERVER = 20;
  var_dump($_SERVER += 10);

  class C { public static $a; }
  C::$a = 20;
  var_dump(C::$a += 10);
}
main();
