public function writeOpeningTag($newline = true)
    {
        try {
            $this->getStream()->write('<?php');
            if ($newline === true) {
                $this->writeNewline();
            }
        } catch (StreamException $e) {
            $msg = "An error occured while writing a PHP opening tag (<?php).";
            throw new StreamAccessException($msg, $this, 0, $e);
        }
    }