def join_map_below(map1, map2): Given two maps, create and return a new map by deep-copying map1 and map2 one above the other for a taller map of the same width. If their widths don't match, return None.

Assume: map1 and map2 are maps as defined above. Remember, you must not modify the original maps.

join_map_below([[1,1],[2,2]], [[3,3],[4,4]]) [[1,1],[2,2],[3,3],[4,4]]

join_map_below([[1]], [[2]]) [[1],[2]]

join_map_below([[1,2],[3,4]], [[5,6,7,8]]) None