def PmfProbLess(pmf1, pmf2):
    """Probability that a value from pmf1 is less than a value from pmf2.

    Args:
        pmf1: Pmf object
        pmf2: Pmf object

    Returns:
        float probability
    """
    total = 0
    for v1, p1 in pmf1.Items():
        for v2, p2 in pmf2.Items():
            if v1 < v2:
                total += p1 * p2
    return total
