n class="type-var">_</span> <a href="#type-t">t</a></span> <span class="arrow">&#45;&gt;</span></span> <span>while_:<span>bool <a href="#type-t">t</a></span> <span class="arrow">&#45;&gt;</span></span> <span>on_take_cb:<span>(<span><span class="type-var">'a</span> <span class="arrow">&#45;&gt;</span></span> unit)</span> <span class="arrow">&#45;&gt;</span></span>
<span><span><span class="type-var">'a</span> <a href="#type-t">t</a></span> <span class="arrow">&#45;&gt;</span></span> <span>int <a href="#type-t