lass="line"><code class="docutils literal notranslate"><span class="pre">Predicate</span></code> is a variable:</div>
<div class="line-block">
<div class="line"><code class="docutils literal notranslate"><span class="pre">instantiation_error</span></code></div>
</div>
<div class="line"><code class="docutils literal notranslate"><span class="pre">Functor</span></code> is a variable:</div>
<div class="line-block">
<div class="line"><code class="docutils literal notranslate"><span class="pre">instantiation_err