def calc_query(self):
        """Calculate the sampling query distribution"""
        # initial query
        if self.query_dist is None:
            self.query_dist = self.exp4p_.next(-1, None, None)
        else:
            self.query_dist = self.exp4p_.next(
                self.calc_reward_fn(),
                self.queried_hist_[-1],
                self.dataset.data[self.queried_hist_[-1]][1]
            )
        return
Calculate the sampling query distribution