If it is a list it will append the obj, if it is a dictionary
        it will convert it to a list and append
        :param obj: dict or list of the object to append
        :return: None

def append(self, obj):
        """
        If it is a list it will append the obj, if it is a dictionary
        it will convert it to a list and append
        :param obj: dict or list of the object to append
        :return: None
        """
        if isinstance(obj, dict) and self._col_names:
            obj = [obj.get(col, None) for col in self._col_names]
        assert isinstance(obj, list), \
            "obj appended to ReprListList needs to be a list or dict"
        self._original.append(obj)