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                +--------+
                |        |
   +----+       +--^-----+
   |    |          |
   |    +------+---+
   +----+      |
               |       +---+
   +----+      |       |   |
   |    |      |       |   |
   |    |    +-v---+   |   |
   |    <----+     +--->   |
   +----+    +-----+   +---+