Parsing Error: Unexpected T_Variable - Can not figure out why?
<p>I feel stupid to do this, but I am getting this perpetual PARSE_ERROR in the following code (I must be overlooking something very simple here):</p>

<pre><code>function print_article_tree($tree) {
    $tree = traverse_tree($tree);
    $string = '&lt;ul&gt;';
    foreach ($tree as $parent_id=&gt;$nodes) {
        $string .= '&lt;li&gt;&lt;ul&gt;';
        $childs = explode(',',$nodes);
        foreach ($childs as $child) {
            if (!isset($tree[$child])) $string .= '&lt;li&gt;'.$child .'__' $parent_id .'&lt;/li&gt;';
        }
        $string .= '&lt;/ul&gt;&lt;/li&gt;';
    }
    $string .= '&lt;/ul&gt;';
    return $string;
}
</code></pre>

<p>The line giving error is that starts with: <code>if (!isset($tree[$child]))</code><br>
can someone suggest me what I is wrong here?</p>
