    def _tracebackToTree(self, failure):
        backtrace = ET.Element('backtrace')

        frames = failure.stack + failure.frames

        for function_name, filename, line_number, localz, globalz in frames:
            attrib = {'file': filename,
                      'number': str(line_number),
                      'method': "%s: %s" % (
                        function_name,
                        linecache.getline(filename, line_number).strip())}
            backtrace.append(ET.Element('line', attrib=attrib))

        return backtrace