+-------+ +       +           +-------+ +-------+                        
        | |       |           |         |                                
        | |       |     ⊗     |         |                                
        | |       |           |         |                                
+-------+ +-------+           +-------+ +-------+       +---+ +---+ +---+
        |         |                   | |       |   ⊗       | |   | |   |
        |         |     ⊗             | |       |           + +---+ +---+
        |         |                   | |       |   ⊗       | |   |     |
+-------+         +           +-------+ +-------+           + +---+ +---+