code></a> only needs to be commutative with the <a href="index.html#val-empty"><code>empty</code></a> element.</p></aside><div><div class="spec include"><div class="doc"><details open="open"><summary><span class="def"><code><span class="keyword">include</span> <a href="../../../../../../Bastet/Interface/index.html#module-type-SEMIGROUP">Bastet.Interface.SEMIGROUP</a></code></span></summary><div><div class="spec include"><div class="doc"><details open="open"><summary><span class="def"><code><span class="keyw