index contains paths to header files.</p></div></div><div class="odoc-spec"><div class="spec value anchored" id="val-invalid"><a href="#val-invalid" class="anchor"></a><code><span><span class="keyword">val</span> invalid : <span>string <span class="arrow">&#45;&gt;</span></span> <a href="#type-t">t</a></span></code></div><div class="spec-doc"><p>Invalid source file</p></div></div><div class="odoc-spec"><div class="spec value anchored" id="val-equal"><a href="#val-equal" class="anchor"></a><code><span><span 