mpty</a>() const;
</pre>

<b>Returns:</b> <tt>true</tt> if <tt>this->size() == 0</tt>, <tt>false</tt>
otherwise. <i>Note</i>: not to be confused with <tt>none()</tt>, that has
different semantics.

<hr />
<pre>
size_type <a id="capacity">capacity</a>() const;
</pre>

<b>Returns:</b>  The total number of elements that <tt>*this</tt> can hold without requiring
reallocation.<br />
<b>Throws:</b> nothing.

<hr />
<pre>
void <a id="reserve">reserve</a>(size_type num_bits);
</pre>

<b>Effects:</b> A directive tha