ing">"%setfield0"</span><br>
&nbsp;&nbsp;<span class="keyword">external</span>&nbsp;incr&nbsp;:&nbsp;int&nbsp;<span class="constructor">Pervasives</span>.ref&nbsp;<span class="keywordsign">-&gt;</span>&nbsp;unit&nbsp;=&nbsp;<span class="string">"%incr"</span><br>
&nbsp;&nbsp;<span class="keyword">external</span>&nbsp;decr&nbsp;:&nbsp;int&nbsp;<span class="constructor">Pervasives</span>.ref&nbsp;<span class="keywordsign">-&gt;</span>&nbsp;unit&nbsp;=&nbsp;<span class="string">"%decr"</span><br>
&nbsp;&nbsp;<