I meant that as you have `multi = self._pmap.get("multi", False)` then, if `self._pmap` is an empty dict, you'll have `False`, so the comparison `it not self._pmap` would not be needed.
If you have to check whether `self._pmap` exists or not, I think that the current `empty()` will not suffice, since a reference to a non existing variable raises `NameError` and you're not catching that.