class="constructor">Misc</span>.<span class="constructor">Stdlib</span>.<span class="constructor">String</span><br>
&nbsp;&nbsp;<span class="keyword">type</span>&nbsp;map_tree&nbsp;=&nbsp;<span class="constructor">Node</span>&nbsp;<span class="keyword">of</span>&nbsp;<span class="constructor">String</span>.<span class="constructor">Set</span>.t&nbsp;*&nbsp;<span class="constructor">Depend</span>.bound_map<br>
&nbsp;&nbsp;<span class="keyword">and</span>&nbsp;bound_map&nbsp;=&nbsp;<span class="constructor">D