<span style="color: #0000BB">$now</span><span style="color: #007700">=</span><span style="color: #0000BB">microtime</span><span style="color: #007700">(</span><span style="color: #0000BB">true</span><span style="color: #007700">);<br />&nbsp;&nbsp;&nbsp;&nbsp;while((</span><span style="color: #0000BB">$last</span><span style="color: #007700">=</span><span style="color: #0000BB">array_pop</span><span style="color: #007700">(</span><span style="color: #0000BB">$stack</span><span style="color: #007700">))!==</