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 function f(v1, v2, value)

 {

   var b = v1 != v2;

   assertEq(b, value,

            "failed: " + v1 + ", " + v2 + ": " + value);

 }

 var obj = {};

 var emul = objectEmulatingUndefined();

 f(obj, obj, false);

 f(obj, obj, false);

 f(emul, obj, true);

 f(emul, obj, true);

 f(obj, emul, true);

 f(obj, emul, true);

 f(Object.prototype, obj, true);

 f(Object.prototype, obj, true);

 f(emul, emul, false);

 f(objectEmulatingUndefined(), emul, true);

 f(objectEmulatingUndefined(), emul, true);

 f(emul, objectEmulatingUndefined(), true);

 f(emul, objectEmulatingUndefined(), true);