r or header (end) node. "pos" must be an iterator pointing to the successor to "new_node" once inserted according to the order of already inserted nodes. This function does not check "pos" and this precondition must be guaranteed by the caller.</p>
<p><span class="bold"><strong>Effects</strong></span>: Inserts new_node into the tree before "pos".</p>
<p><span class="bold"><strong>Complexity</strong></span>: Constant-time.</p>
<p><span class="bold"><strong>Throws</strong></span>: Nothing.</p>
<p><span class=