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

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