+----------+     +------+     +------+
|          |     |      |     |      |
|  +-------+     |      |     |      |
|  |             |      |     |      |
|  |  +--+       |      |     |      |
|  |  |  |       |      |     |      |
|  |  +--+       |      |     | +--+ |
|  |             |      |     | |  | |
|  +-------+     +-+--+-+     +-+--+-+
|          |       |  |        
+----------+       +--+