   +----------+ 
   |    x     | 
   |          | 
   +----------+ 
      | |   |   
  +---+ |   +--+
  |     |      |
  |   okay     |
  |     |      |
  v     v      |
 +------+      |
 |  y   |      |
 |      |      |
 +------+      |
        |      |
        |  +---+
        |  |    
        v  v    
     +------+   
     |  z   |   
     |      |   
     +------+   
