docs: def prepare(session_data={}, #pylint: disable=dangerous-default-value
                  passphrase=None):
          """
          Returns *session_dict* as a base64 encrypted json string.
  
          """
          if passphrase is None:
              passphrase = settings.DJAODJIN_SECRET_KEY
          return encode(session_data, passphrase,
              json_encoder=crypt.JSONEncoder)