[D] Any tutorial on importance weighted active learning? • r/MachineLearning

I was reading this interesting paper on importance weighted active learning: http://cseweb.ucsd.edu/ I'm trying to implement a basic example of active learning using sklearn. I'm looking at how to implement the "implicit" version. However, I don't understand the meaning of "If learn(S (xt, 1)) and learn(S (xt, 0)) both return an answer". Is there anyone who can shed some light or point me to resources that'll help me implement importance weighted active learning?