Extra Python Collections - bags (multisets) and setlists (ordered sets)

collections_extended is a pure Python module with no dependencies providing various extended collection types. It includes a bag (multiset) class, a setlist (ordered set / unique list) class, a bijection, a RangeMap, and an IndexedDict. It also offers frozen (hashable) variants of bags and setlists. The current version, 2.0.2, maintains an active development status with regular updates and is compatible with Python 3.7+.