### Question:
Octree { public void remove(int x, int y, int z, int size) { if (size == level && this.item != null) { this.item = null; return; } for (int i = 0; i < 8; ++i) { if (octants[i] != null && octants[i].containsPoint(x, y, z)) { octants[i].remove(x, y, z, size); break; } } } Octree();  Octree(int rootLevel); private  Octree(int level, int x, int y, int z); void clear(); void remove(int x, int y, int z, int size); void insert(int x, int y, int z, int size, T item); Octree get(int octant); int getLevel(); T getItem(); int getItemCount(); T get(int x, int y, int z, int size); List<T> flatten();  }### Answer:
@Test public void testRemove() { Octree<Integer> o = new Octree<>(6); o.insert(0, 0, 0, 8, 42); assertEquals(1, o.getItemCount()); o.remove(0, 0, 0, 8); assertEquals(0, o.getItemCount()); }