This example is taken from: http://rt.cpan.org/Public/Bug/Display.html?id=20879

               ---     ---     ---
Level 5     8 | A | 9 | B | A | C |    (More General)
               ---     ---     ---       V
                  \     |     /          |
                   \    |    /           |
                    \   |   /            |
                     \  |  /             |
                       ---               |
Level 4             7 | D |              |
                       ---               |
                      /   \              |
                     /     \             |
                  ---       ---          |
Level 3        4 | G |   6 | E |         |
                  ---       ---          |
                   |         |           |
                   |         |           |
                  ---       ---          |
Level 2        3 | H |   5 | F |         |
                  ---       ---          |
                      \   /  |           |
                       \ /   |           |
                        \    |           |
                       / \   |           |
                      /   \  |           |
                  ---       ---          |
Level 1        1 | J |   2 | I |         |
                  ---       ---          |
                    \       /            |
                     \     /             |
                       ---               v
Level 0             0 | K |            (More Specialized)
                       ---

0123456789A KJIHGFEDABC