 href="#val-is_false" class="anchor"></a><code><span class="keyword">val</span> is_false : <a href="index.html#type-t">t</a> <span>&#45;&gt;</span> bool</code></dt><dt class="spec value" id="val-is_true"><a href="#val-is_true" class="anchor"></a><code><span class="keyword">val</span> is_true : <a href="index.html#type-t">t</a> <span>&#45;&gt;</span> bool</code></dt><dt class="spec value" id="val-not_"><a href="#val-not_" class="anchor"></a><code><span class="keyword">val</span> not_ : <a href="index.html#ty