Time when access token was requested, as seconds since epoch.

        Note:
            Accessing this property when there wasn't any request attempts
            will return current time.

        Returns:
            int

def issued_at(self):
        """Time when access token was requested, as seconds since epoch.

        Note:
            Accessing this property when there wasn't any request attempts
            will return current time.

        Returns:
            int
        """
        issued_at = self._issued_at
        if issued_at is None:
            self._issued_at = int(time.time())
        return self._issued_at