 +----+    +------------------->+----+             
 |    |    |                    |    |             
 |    |----+                    | y  |             
 | x  |----------okay---------->|    |------>+----+
 |    |                         +----+       | z  |
 |    |----+                             +-->|    |
 |    |    |                             |   +----+
 +----+    +-----------------------------+         
