those words or you just have to predict the future from the past or the past from the future or present from the past like loss a various different versions depending on the mask so this way the data is creating its own supervision and you can perfect you can ask a neural network we'll learn a lot more than just predicting labels so the details obviously decide what is a proxy loss or what is the pretext ask you can think about all these withhold and predict classes some kind of pretext ask and you can think of whatever details you use