def jaccard(A: set, B: set) -> float:
    """Jaccard Similarity Coefficient or Intersection over Union

    Parameters:
    -----------
    A, B : set
        Sets of unique shingles

    Return:
    -------
    metric : float
        The Jaccard Similarity Coefficient
    """
    u = float(len(A.intersection(B)))
    return u / (len(A) + len(B) - u)