<b>Throws:</b> nothing.

<hr />
<pre>
bool <a id="none">none</a>() const
</pre>

<b>Returns:</b> <tt>true</tt> if no bits are set, and otherwise
returns <tt>false</tt>.<br />
<b>Throws:</b> nothing.

<hr />
<pre>
bool <a id="test">test</a>(size_type n) const
</pre>

<b>Precondition:</b> <tt>n &lt; this-&gt;size()</tt>.<br />
 <b>Returns:</b> <tt>true</tt> if bit <tt>n</tt> is set and
<tt>false</tt> is bit <tt>n</tt> is 0.

<hr />
<pre>
bool <a id="test">test_set</a>(size_type n, bool val = true)
</pre>

<b>