To create a signed JWT
    :param data:
    :param secret_key:
    :param expires_in:
    :param salt:
    :param kw:
    :return: string

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