public void DeleteVolumes(IEnumerable <Volume> volumes)
{
var gets = volumes.Select(v => _compute.GetVolumeAsync(v.Id)).ToArray();
Task.WaitAll(gets);
var serverDeletes = gets.SelectMany(v => v.Result.Attachments.Select(a => a.ServerId))
.Select(serverId => _compute.WaitUntilServerIsDeletedAsync(serverId)).ToArray();
Task.WaitAll(serverDeletes);
var deletes = volumes.Select(x => x.DeleteAsync()).ToArray();
Task.WaitAll(deletes);
}