Here we have a second example from the overlapping square region network.
This cluster clearly groups 2's and 7's together; howeverm a few odd 3's have
snuck in, not to mention the lone 9.

                               | |     |-| |-> 0
                               | |       |_|-> 0
                               | |         |-> 0
                               | |   |-> 9
                               | |   | |-> 2
                               |-|   | |   |-> 7
                                 | |-| | |-|  _|-> 3
                                 | | | | | | | |_|-> 3
                                 | | | | | |-|   |-> 3
                                 | | | | |   | |-> 2
                                 | | |-| |   |-| |-> 7
                                 | |   | |     | | |-> 2
                                 | |   | |     |-| |   |-> 7
                                 | |   | |       | | |-| |-> 3
                                 | |   | |       | | | |-|  _|-> 2
                                 | |   | |       |-| |   | | |-> 2
                                 | |   |-|         | |   |-|  _|-> 2
                                 | |     |         | |     | | |_|-> 2
                                 | |     |         | |     | |   |_|-> 2
                                 | |     |         |-|     |-|     |-> 2
                                 |-|     |           |       | |-> 7
                                   |     |           |       |-|  _|-> 7
                                   |     |           |         |-| |-> 7
                                   |     |           |           |_|-> 2
                                   |     |           |             |_|-> 2
                                   |     |           |               |-> 2
                                   |     |           |-> 2
                                   |     |-> 7