function testReconfigureAsAccessorProperty(f) {
  var length = 2;
  Object.defineProperty(f, 'length', {
    get: function () {
      return length;
    },
    set: function (v) {
      length = v;
    }
  });
}
(function testSetOnInstance() {
  function f() {}
  delete f.length;
  testReconfigureAsAccessorProperty(f);
  Object.defineProperty(Function.prototype, 'length', {
    writable: true
  });
  f.length = 123;
  print(f.length); // It should print 123; but print 0
})();