Fit Unary Math Operator
        :param y:
        :return:

def fit(self, X, y=None, **fit_params):
        """
        Fit Unary Math Operator
        :param y:
        :return:
        """
        if self.transform_type not in self.valid_transforms:
                warnings.warn("Invalid transform type.", stacklevel=2)
        return self