def get_custom_label_attribute(self, attribute):
        """
        Get a list of the custom_labels attribute.
        ie. label_store, symbol, or description.

        The custom_labels variable could be in
        a number of formats
        """

        if attribute not in ann_label_fields:
            raise ValueError('Invalid attribute specified')

        if isinstance(self.custom_labels, pd.DataFrame):
            if 'label_store' not in list(self.custom_labels):
                raise ValueError('label_store not defined in custom_labels')
            a = list(self.custom_labels[attribute].values)
        else:
            if len(self.custom_labels[0]) == 2:
                if attribute == 'label_store':
                    raise ValueError('label_store not defined in custom_labels')
                elif attribute == 'symbol':
                    a = [l[0] for l in self.custom_labels]
                elif attribute == 'description':
                    a = [l[1] for l in self.custom_labels]
            else:
                if attribute == 'label_store':
                    a = [l[0] for l in self.custom_labels]
                elif attribute == 'symbol':
                    a = [l[1] for l in self.custom_labels]
                elif attribute == 'description':
                    a = [l[2] for l in self.custom_labels]

        return a
Get a list of the custom_labels attribute.
        ie. label_store, symbol, or description.

        The custom_labels variable could be in
        a number of formats