Undefined variable: array about purify HOT 1 CLOSED

public function purifyArray($array_of_html, $config = null)
{
    $context_array = array();
    $array = array();
    foreach($array_of_html as $key=>$value){
        if (is_array($value)) {
           $array[$key] = $this->purifyArray($value, $config);
        } else {
            $array[$key] = $this->purify($value, $config);
        }
        $context_array[$key] = $this->context;
    }
    $this->context = $context_array;
    return $array;
}