def _reverse_lookup(idx: int, types: [str]) ->str:
    """
    Converts an integer value back to the string representation
    :param idx: integer value
    :param types: list of types
    :return: the string value or None if not found (idx == 0)
    """
    if idx == 0:
        return ''
    else:
        return types[idx - 1]
