'get_circuit(circuit_id, default = UNDEFINED)
Provides a circuit currently available from tor.
:param int circuit_id: circuit to be fetched
:param object default: response if the query fails
:returns: :class:`stem.response.events.CircuitEvent` for the given circuit
:raises:
* :class:`stem.ControllerError` if the call fails
* **ValueError** if the circuit doesn\'t exist
An exception is only raised if we weren\'t provided a default response.'

@with_default()
def get_circuit(self, circuit_id, default=UNDEFINED):

    for circ in self.get_circuits():
        if (circ.id == circuit_id):
            return circ
    raise ValueError(("Tor    currently    does    not    have    a    circuit    with    the    id    of    '%s'" % circuit_id))
