+---+     +---+
| E | --> | D | -+
+---+     +---+  v
            |  +---+
            +> | C | <+
               +---+  |
                 ^  +---+
                 +- | B | ------+
                    +---+       v
                      ^       +---+
                      +------ | A |
                              +---+