 in the Tree.</p>

<h3 class="function"><a name="get_ph-1">get_ph/1</a></h3>
<div class="spec">
<p><tt>get_ph(Node::<a href="tree.html#type-tree_node">tree:tree_node()</a>) -&gt; {node, <a href="tree.html#type-tree_ph">tree:tree_ph()</a>} | {node_pair, <a href="tree.html#type-tree_ph">tree:tree_ph()</a>, <a href="tree.html#type-tree_ph">tree:tree_ph()</a>}</tt><br></p>
</div><p>
  Returns the placeholder for a node or node pair Node. That is,
  an unique identifier for the Node, that is used as placeholder
