odule-type-Arg">Arg</a>) <span>&#45;&gt;</span> <span class="keyword">sig</span> ... <span class="keyword">end</span></code></div><dl><dt class="spec exception" id="exception-UserAlreadyDefined"><a href="#exception-UserAlreadyDefined" class="anchor"></a><code><span class="keyword">exception</span> </code><code><span class="exception">UserAlreadyDefined</span></code></dt><dt class="spec exception" id="exception-NoPasswordProvided"><a href="#exception-NoPasswordProvided" class="anchor"></a><code><span class="