+--------+----------------------------------+
| bitmap | 00000000000000010000001000000000 |
+--------+----------------------------------+
|        | +-+-+                            |
| array  | | | |                            |
|        | +++++                            |
+--------+--+-+-----------------------------+
            | |
            | +------------+
            |              |
            v              v
       /----------\  +-----------+
       | bar → 17 |  | (subtrie) |
       \----------/  +-----------+