remove current front Item from list
+--------------+-----------------------+-----------------+
| this | other | list |
| Iter | Iter | |
+--------------+-----------------------+-----------------+
| remove list | if points to removed: | free item; |
| item; | mark invalid | adjust counters |
| do popFront; | else: | |
| | adjust everything | |
+--------------+-----------------------+-----------------+
remove current front Item from list +--------------+-----------------------+-----------------+ | this | other | list | | Iter | Iter | | +--------------+-----------------------+-----------------+ | remove list | if points to removed: | free item; | | item; | mark invalid | adjust counters | | do popFront; | else: | | | | adjust everything | | +--------------+-----------------------+-----------------+