pairs=[{'ad': 'q_topic_1', 'pos_hist': 'm_interested_topics'}, {'ad': 'q_topic_2', 'pos_hist': 'm_interested_topics'}, {'ad': 'q_topic_3', 'pos_hist': 'm_interested_topics'}, {'ad': 'q_topic_4', 'pos_hist': 'm_interested_topics'}, {'ad': 'q_topic_5', 'pos_hist': 'm_interested_topics'} ],