'Yields the sentence as an XML-formatted string (plain bytestring, UTF-8 encoded).
All the sentences in the XML are wrapped in a <text> element.'

@property
def xml(self):

    xml = []
    xml.append(('<?xml    version="1.0"    encoding="%s"?>' % XML_ENCODING.get(self.encoding, self.encoding)))
    xml.append(('<%s>' % XML_TEXT))
    xml.extend([sentence.xml for sentence in self])
    xml.append(('</%s>' % XML_TEXT))
    return '\n'.join(xml)
