nbsp;&nbsp;<span class="keyword">external</span>&nbsp;succ&nbsp;:&nbsp;int&nbsp;<span class="keywordsign">-&gt;</span>&nbsp;int&nbsp;=&nbsp;<span class="string">"%succint"</span><br>
&nbsp;&nbsp;<span class="keyword">external</span>&nbsp;pred&nbsp;:&nbsp;int&nbsp;<span class="keywordsign">-&gt;</span>&nbsp;int&nbsp;=&nbsp;<span class="string">"%predint"</span><br>
&nbsp;&nbsp;<span class="keyword">external</span>&nbsp;(&nbsp;+&nbsp;)&nbsp;:&nbsp;int&nbsp;<span class="keywordsign">-&gt;</span>&nbsp;int&nbsp;