code: def _default_styles_xml(cls):
          
          path = os.path.join(
              os.path.split(__file__)[0], '..', 'templates',
              'default-styles.xml'
          )
          with open(path, 'rb') as f:
              xml_bytes = f.read()
          return xml_bytes
docs: Return a bytestream containing XML for a default styles part.