<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def add_circuit_breaker(self, circ_breaker):
 Args ---- circ_breaker: CircuitBreakerDing0 Description #TODO """

        if circ_breaker not in self._circuit_breakers and isinstance(circ_breaker, CircuitBreakerDing0):
            self._circuit_breakers.append(circ_breaker)
            self.graph_add_node(circ_breaker)