'resume the specified suspended instance.
The suspended instance gets resumed and will use CPU cycles and memory
of the host again. The counter action for \'resume\' is :func:`suspend`.
Depending on the underlying hypervisor technology, the guest has the
same state as before the \'suspend\'.
:param nova.context.RequestContext context:
The context for the resume.
:param nova.objects.instance.Instance instance:
The suspended instance to resume.
:param nova.network.model.NetworkInfo network_info:
Necessary network information for the resume.
:param dict block_device_info:
Instance volume block device info.
:return: None'

def resume(self, context, instance, network_info, block_device_info=None):

    raise NotImplementedError()
