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 var a = [1,2,3,4];

 // Basic constants.

 function foo(x) {

   return x[0] + x[1] + x[2] + x[3];

 }

 for (var i = 0; i < 100; i++)

   assertEq(foo(a), 10);

 assertEq(foo([1,2,3]), NaN);

 // Basic terms.

 function foo2(x, n) {

   return x[n] + x[n + 1] + x[n + 2];

 }

 for (var i = 0; i < 100; i++)

   assertEq(foo2(a, 1), 9);

 assertEq(foo2(a, 2), NaN);

 // Term underflow.

 function foo3(x, n) {

   return x[n] + x[n + 1] + x[n + 2];

 }

 for (var i = 0; i < 100; i++)

   assertEq(foo3(a, 1), 9);

 assertEq(foo3(a, -1), NaN);

 // Integer overflow computing bound.

 function foo4(x, n) {

   return x[n] + x[n + 1] + x[n + 2];

 }

 for (var i = 0; i < 45; i++)

   assertEq(foo4(a, 1), 9);

 assertEq(foo4(a, 0x7fffffff), NaN);

 // Underflow at an offset.

 function foo5(x, n) {

   return x[n + 10] + x[n + 11] + x[n + 12];

 }

 for (var i = 0; i < 45; i++)

   assertEq(foo5(a, -9), 9);

 assertEq(foo5(a, -11), NaN);

 // Overflow at offset.

 function foo6(x, n) {

   return x[n - 10] + x[n - 11] + x[n - 12];

 }

 for (var i = 0; i < 45; i++)

   assertEq(foo6(a, 13), 9);

 assertEq(foo6(a, 14), NaN);