'Return bandwidth usage counters for each interface on each
running VM.'

def get_all_bw_counters(self, instances):

    bw = []
    for instance in instances:
        bw.append({'uuid': instance.uuid, 'mac_address': 'fa:16:3e:4c:2c:30', 'bw_in': 0, 'bw_out': 0})
    return bw
