def score_to_flag(score: float):
    """Classify an inappropriateness probability into discreet categories.

    "param score: float (0.0 -> 1.0), required.

    Returns:
    int: 0 = OK, 1 = REVIEW, 2 = BLOCK
    """
    assert isinstance(score, float), f'score type ({type(score)}) not float.'
    assert score >= 0.0 and score <= 1.0, \
        f'Score ({score}) outside acceptable range (0->1).'
    if score < 0.2:
        return 0
    elif score < 0.95:
        return 1
    else:
        return 2