Question: Who completed Prokofiev's Cello Concertino with a Russian composer born in 1904?
{'answer': 'Mstislav Rostropovich', 'supporting_facts': [['Cello Concertino (Prokofiev)', 0], ['Cello Concertino (Prokofiev)', 1], ['Cello Concertino (Prokofiev)', 2], ['Dmitry Kabalevsky', 0]]}