code: def next(self, reward, ask_id, lbl):
          
          # first run don't have reward, TODO exception on reward == -1 only once
          if reward == -1:
              return next(self.exp4p_gen)
          else:
              # TODO exception on reward in [0, 1]
              return self.exp4p_gen.send((reward, ask_id, lbl))
docs: Taking the label and the reward value of last question and returns
          the next question to ask.