def ACC_calc(TP, TN, FP, FN):
    """
    Calculate accuracy.

    :param TP: true positive
    :type TP : int
    :param TN: true negative
    :type TN : int
    :param FP: false positive
    :type FP : int
    :param FN: false negative
    :type FN : int
    :return: accuracy as float
    """
    try:
        result = (TP + TN) / (TP + TN + FN + FP)
        return result
    except ZeroDivisionError:
        return "None"