done a lot of kind of Appalachian studies where they show that it's really due to the fact that they do this left and right context they they take into account the left and right context of given token when doing the the attention that it's that that's why it's better so here for example they compare the bird base model and they say okay what if we don't do the NSP the next sentence prediction tasks then you can see the numbers they already kind of they drop on these tasks and what if we then additionally do only left-to-right