     boeket         bloemen
       |              |
       |     ___ ___  |     ___ ___      ___ ___
        --> |   |   |  --> |   |   |    |   |   |
            |___|___|----> |___|___|--> |___|___|--> nil
              |              |            |
              |              |            |
               --> roos       --> viool    --> boterbloem
