
       +---------+         +---------+
       |         v         v         |
     +---+     +-------------+     +---+
     |   | --> |      C      | --> | D |
     | B |     +-------------+     +---+
     |   |       ^
  +->|   | ------+
  |  +---+
  |    ^
  |    |
  |    |
  |  +--------+     +---+
  +--|   A    | --> | F |
     +--------+     +---+
       |
       |
       v
     +---+
     | G |
     +---+
