A simple implementation of immutable multiset

multiset.py

from collections import Counter

class combs:
    """
    A simple implementation of immutable multiset
    """
    def __init__(self, seq):
        s = set(seq)
        if len(seq) == len(s):
            self._save = s
            self._unique = True
            self._counts = Counter(s)
        else:
            self._save = tuple(seq)
            self._unique = False
            self._counts = Counter(seq)

    def __eq__(self, comb):
        if isinstance(comb, self.__class__):
            return self.__dict__['_counts'] == comb.__dict__['_counts']
        else:
            return False

    def __repr__(self):
        return f"combs({', '.join([str(s) for s in self._save])})"

    def __str__(self):
        return ', '.join([str(s) for s in self._save])

    def __iter__(self):
        yield from self._save

    def __hash__(self):
        if self._unique:
            return hash(frozenset(self._save))
        else:
            return hash(frozenset([(k, v) for k, v in self._counts.items()]))

    def __dir__(self):
        return dir(super(combs, self))[:-1]