C
castironpi
Nothing else should have direct access to the list.
If the list is not too long, that is reasonable. If it -is- long, the
remove operations can be slow, but that's ok if there's not too many.
If the list is long -and- there's a lot of adds/removes, maybe you
want something like an AVL tree.
But items[ item ]= index is the best I can do in Python.