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