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 // Test for-of with iter.next and monkeypatching.

 function* g(n) { for (var i=0; i<n; i++) yield i; }

 var GeneratorObjectPrototype = Object.getPrototypeOf(g).prototype;

 var GeneratorObjectPrototype_next = GeneratorObjectPrototype.next;

 // Monkeypatch next on an iterator.

 var inner = g(20);

 var n = 0;

 for (let x of inner) {

     if (n == 0) {

         assertEq(x, n++);

     } else if (n == 1) {

         assertEq(x, n++);

         inner.next = function() { return { value: 42, done: false }; };

     } else if (n == 2) {

         assertEq(x, 42);

         inner.next = function() { return { value: 100, done: true }; };

     } else

         throw 'not reached';

 }

 // Monkeypatch next on the prototype.

 var inner = g(20);

 var n = 0;

 for (let x of inner) {

     if (n == 0) {

         assertEq(x, n++);

     } else if (n == 1) {

         assertEq(x, n++);

         GeneratorObjectPrototype.next =

             function() { return { value: 42, done: false }; };

     } else if (n == 2) {

         n++;

         assertEq(x, 42);

         GeneratorObjectPrototype.next = GeneratorObjectPrototype_next;

     } else if (n <= 20) {

         assertEq(x, n++ - 1);

     } else

         throw 'not reached';

 }