sequence of uniformly distributed non-deterministic random
numbers. For those environments where a non-deterministic random
number generator is not available, class <code>random_device</code>
must not be implemented.  See
<blockquote>
"Randomness Recommendations for Security", D. Eastlake, S.
Crocker, J. Schiller, Network Working Group, RFC 1750, December 1994
</blockquote>
for further discussions.

<p>
<em>Note:</em> Some operating systems abstract the computer hardware
enough to make it difficult to non-i