def _get_categories(self):
        """
        :rtype: list(str) or list(list(str))
        """
        category_list = []
        for child in self.vcard.getChildren():
            if child.name == "CATEGORIES":
                value = child.value
                category_list.append(
                    value if isinstance(value, list) else [value])
        if len(category_list) == 1:
            return category_list[0]
        return sorted(category_list)
:rtype: list(str) or list(list(str))