from typing import Iterable
from typing import Counter


def smallest_largest_clusters_ratio(_, labels: Iterable) -> float:
    """Number in the smallest cluster over the number in the largest cluster.  

    Args: 
        _: Dummy, pass anything or None.  
        labels (Iterable): Vector of sample labels.  

    Returns (float): 
        Ratio of number of members in smallest over largest cluster.  

    """
    counts = Counter(labels)
    counts.pop(-1, None)
    return min(counts.values()) / max(counts.values())