Prints out the summary of validation for giving scoring function.

def summary(self, scoring):
        """
        Prints out the summary of validation for giving scoring function.
        """

        if scoring == 'class_confusion':
            print('*' * 50)
            print('  Confusion Matrix ')
            print('x-axis: ' + ' | '.join(list(self.class_dictionary.keys())))
            print('y-axis: ' + ' | '.join(self.truth_classes))
            print(self.confusion_matrix())