an></span> bool</span></code></div></div><div class="odoc-spec"><div class="spec value anchored" id="val-is_weak"><a href="#val-is_weak" class="anchor"></a><code><span><span class="keyword">val</span> is_weak : <span><a href="#type-t">t</a> <span class="arrow">&#45;&gt;</span></span> <span>bool option</span></span></code></div></div><div class="odoc-spec"><div class="spec value anchored" id="val-is_capture_field_in_closure_by_ref"><a href="#val-is_capture_field_in_closure_by_ref" class="anchor"></a><code><s