Start serialization -- open the XML document and the root element.

def start_serialization(self):
        """
        Start serialization -- open the XML document and the root element.
        """
        if (self.root):
            self.xml = XmlPrinter(self.stream, self.options.get("encoding", settings.DEFAULT_CHARSET))
            self.xml.startDocument()
            self.xml.startElement("django-objects", {"version" : "1.0"})