How to get long long mask by number?
<p>Say to list all masks we use:</p>

<pre><code>for (unsigned long long mask = 1; mask != 0; mask &lt;&lt;= 1) {

}
</code></pre>

<p>but here we move using operator <code>&lt;&lt;=</code> one by one our mask value, how to step over to mask number <code>20</code> or <code>55</code>?</p>
