span>}</span></code></div></div><div class="odoc-spec"><div class="spec value anchored" id="val-fail_test"><a href="#val-fail_test" class="anchor"></a><code><span><span class="keyword">val</span> fail_test : <span>string <span class="arrow">&#45;&gt;</span></span> <span class="type-var">'a</span></span></code></div></div><div class="odoc-spec"><div class="spec value anchored" id="val-user_error"><a href="#val-user_error" class="anchor"></a><code><span><span class="keyword">val</span> user_error : <span>stri