* of the returned array is that of the specified array. If the collection fits in the specified
   * array, it is returned therein. Otherwise, a new array is allocated with the runtime type of the
   * specified array and the size of the specified collection.
   *
   * <p>If the collection fits in the specified array with room to spare (i.e., the array has more

</p>

<p>
If the capacity of <code>s</code> is not large enough to fit the additional
values, <code>append</code> <a href="#Allocation">allocates</a> a new, sufficiently large underlying
array that fits both the existing slice elements and the additional values.
Otherwise, <code>append</code> re-uses the underlying array.
</p>

<pre>
s0 := []int{0, 0}

bits, which guarantees // that all carries are at most 111 - 51 = 60 bits, which fits in a uint64. // // r0 = a0×b0 + 19×(a1×b4 + a2×b3 + a3×b2 + a4×b1) // r0 < 2⁵²×2⁵² + 19×(2⁵²×2⁵² + 2⁵²×2⁵² + 2⁵²×2⁵² + 2⁵²×2⁵²) // r0 < (1 + 19 × 4) × 2⁵² × 2⁵² // r0 < 2⁷ × 2⁵² × 2⁵² // r0 < 2¹¹¹ // // Moreover, the top coefficient (r4) is at most 107 bits, so c4 is at most // 56 bits, and c4 * 19 is at most 61 bits, which again fits in a uint64 and // allows us to easily apply the reduction identity. // // r4 =...