Calculate IBA_alpha score.

        :param alpha: alpha parameter
        :type alpha: float
        :return: IBA_alpha score for classes as dict

def IBA_alpha(self, alpha):
        """
        Calculate IBA_alpha score.

        :param alpha: alpha parameter
        :type alpha: float
        :return: IBA_alpha score for classes as dict
        """
        try:
            IBA_dict = {}
            for i in self.classes:
                IBA_dict[i] = IBA_calc(self.TPR[i], self.TNR[i], alpha=alpha)
            return IBA_dict
        except Exception:
            return {}