Python Multiset combinations

ms_combinations.py

from collections import Counter as Multiset


def multiset_combinations(ms, n):
    assert sum(ms.values()) >= n
    def f(ms_res, curr_val, ms_rem):
        nonlocal n
        if sum(ms_res.values()) == n:  #ideally len would return the number of total elements
            yield ms_res
        else:
            for val in set(ms_rem):
                if val >= curr_val:
                    # for each unique value in remaining multiset equal to or larger than the current value
                    val_ms = Multiset((val,))  # ideally I wouldn't need to wrap a singleton multiset
                    # add that value to the result multiset and remove it from remaining multiset
                    yield from f(ms_res + val_ms, val, ms_rem - val_ms)
                    # recurse
    yield from f(Multiset(), sorted(ms.keys())[0], ms)

for m in multiset_combinations(Multiset((3, 3, 4, 4, 4, 5)), 3):
    print(list(m.elements()))