+---------------+
       |   +-------+   |
JACK ----->|-> A ->|---+
       |   |       |
       +-->|-> B ->|----------> JACK
           +-------+


           +-------+
           |       |
       +---|<- C <-|<--+
       |   |       |   |
       |   +-------+   |
       |               |
       |   +-------+   |
JACK ----->|-> A ->|---+
       |   |       |
       +-->|-> B ->|----------> JACK
           +-------+