rd number as a string of digits, </span>
<span class="comment">// and reformat it as a human readable string with "-"</span>
<span class="comment">// separating each group of four digit;, </span>
<span class="comment">// note that we're mixing a UTF-32 regex, with a UTF-16</span>
<span class="comment">// string and a UTF-8 format specifier, and it still all </span>
<span class="comment">// just works:</span>
<span class="comment">//</span>
<span class="keyword">const</span> <span class="identifier">boost</s