How to get answerability scores from QA models?

Hi,

models trained on SQuAD 2.0 usually have some way of determining whether the provided context contains the answer or not. E.g. in RoBERTa they say they have trained an additional classifier to predict this. How do I get the model outputs for this classifier? (Or more general how do I get these for any model trained on SQuAD 2.0)?