def micro_calc(item1, item2):
    """
    Calculate TPR, TNR, PPV, FNR, FPR, or F1 micro.

    :param item1: item1 in micro averaging
    :type item1:dict
    :param item2: item2 in micro averaging
    :type item2: dict
    :return: PPV, TPR, TNR, FNR, FPR, or F1 micro as float
    """
    try:
        item1_sum = sum(item1.values())
        item2_sum = sum(item2.values())
        return item1_sum / (item1_sum + item2_sum)
    except Exception:
        return "None"