'Estimate the virtualization overhead required to build an instance
of the given flavor.
Defaults to zero, drivers should override if per-instance overhead
calculations are desired.
:param instance_info: Instance/flavor to calculate overhead for.
:returns: Dict of estimated overhead values.'

def estimate_instance_overhead(self, instance_info):

    return {'memory_mb': 0, 'disk_gb': 0, 'vcpus': 0}
