+--------+----------------------------------+
| bitmap | 00000000000000000000010000010000 |
+--------+----------------------------------+
|        | +-+-+                            |
| array  | | | |                            |
|        | +++++                            |
+--------+--+-+-----------------------------+
            | |
            | +----------+
            |            |
            v            v
       /---------\  /---------\
       | foo → 1 |  | bar → 2 |
       \---------/  \---------/