code: def sample(self, batch_size, batch_idxs=None):
          
          if batch_idxs is None:
              batch_idxs = sample_batch_indexes(0, self.nb_entries, size=batch_size)
          assert len(batch_idxs) == batch_size
  
          batch_params = []
          batch_total_rewards = []
          for idx in batch_idxs:
              batch_params.append(self.params[idx])
              batch_total_rewards.append(self.total_rewards[idx])
          return batch_params, batch_total_rewards
docs: Return a randomized batch of params and rewards
  
          # Argument
              batch_size (int): Size of the all batch
              batch_idxs (int): Indexes to extract
          # Returns
              A list of params randomly selected and a list of associated rewards