graph TD
X
subgraph one
    A --> B
end
Y
X --> A
B --> Y
---
  +---+  
  |   |  
  | X |  
  |   |  
  +---+  
    |    
    |    
    |    
    |    
    |    
+---|---+
|  one  |
|   |   |
|   v   |
| +---+ |
| |   | |
| | A | |
| |   | |
| +---+ |
|   |   |
|   |   |
|   |   |
|   |   |
|   v   |
| +---+ |
| |   | |
| | B | |
| |   | |
| +---+ |
|   |   |
+---|---+
    |    
    |    
    v    
  +---+  
  |   |  
  | Y |  
  |   |  
  +---+  
