};
typedef map < Tuple<int, 2>, Skyline> Chord_outline_map;
typedef map < Tuple<int, 2>, Box> Column_extent_map;
typedef map <int, Slice> Position_extent_map;
};
typedef map < Tuple<int, 2>, Skyline> Chord_outline_map;
typedef map < Tuple<int, 2>, Box> Column_extent_map;
typedef map <int, Slice> Position_extent_map;