class="keyword">val</span> ff_bb : <span><a href="../../A/index.html#type-arr">A.arr</a> <span class="arrow">&#45;&gt;</span></span> <span><a href="../../A/index.html#type-arr">A.arr</a> <span class="arrow">&#45;&gt;</span></span> <a href="../../index.html#type-t">t</a></span></code></div></div><div class="odoc-spec"><div class="spec value anchored" id="val-df_da"><a href="#val-df_da" class="anchor"></a><code><span><span class="keyword">val</span> df_da : <span><a href="../../index.html#type-t">t</a> <span 