def triggered_token(self) -> 'CancelToken':
        """
        Return the token which was triggered.

        The returned token may be this token or one that it was chained with.
        """
        if self._triggered.is_set():
            return self
        for token in self._chain:
            if token.triggered:
                # Use token.triggered_token here to make the lookup recursive as self._chain may
                # contain other chains.
                return token.triggered_token
        return None
Return the token which was triggered.

        The returned token may be this token or one that it was chained with.