code: def sign_jwt(data, secret_key, expires_in, salt=None, **kw):
      
      s = itsdangerous.TimedJSONWebSignatureSerializer(secret_key=secret_key,
                                                       expires_in=expires_in,
                                                       salt=salt,
                                                        **kw)
      return s.dumps(data)
docs: To create a signed JWT
      :param data:
      :param secret_key:
      :param expires_in:
      :param salt:
      :param kw:
      :return: string