How to use the pycm.pycm_class_func.TI_calc function in pycm

def TI(self, alpha, beta):
        """
        Calculate Tversky index.

        :param alpha: alpha coefficient
        :type alpha : float
        :param beta: beta coefficient
        :type beta: float
        :return: TI as float
        """
        try:
            TI_dict = {}
            for i in self.classes:
                TI_dict[i] = TI_calc(
                    self.TP[i], self.FP[i], self.FN[i], alpha, beta)
            return TI_dict
        except Exception:
            return {}