'Perform a reboot on all given \'instances\'.
Reboots the given `instances` which are longer in the rebooting state
than `timeout` seconds.
:param int timeout:
The timeout (in seconds) for considering rebooting instances
to be stuck.
:param list instances:
A list of nova.objects.instance.Instance objects that have been
in rebooting state longer than the configured timeout.
:return: None'

def poll_rebooting_instances(self, timeout, instances):

    raise NotImplementedError()
