bouquet                       flowers
       |                             |
       |     ___ ___        ___ ___  |     ___ ___       ___ ___
        --> |   |   |      |   |   |  --> |   |   |     |   |   |
            |___|___|----> |___|___|----> |___|___|---->|___|___|--> nil
              |              |              |             |
              |              |              |             |
               --> lily      --> rose       --> violet    --> buttercup