expand meta_datas to one level

    Args:
        meta_datas (dict/list): maybe in nested format

    Returns:
        list: expanded list in one level

    Examples:
        >>> meta_datas = [
                [
                    dict1,
                    dict2
                ],
                dict3
            ]
        >>> meta_datas_expanded = []
        >>> __expand_meta_datas(meta_datas, meta_datas_expanded)
        >>> print(meta_datas_expanded)
            [dict1, dict2, dict3]

def __expand_meta_datas(meta_datas, meta_datas_expanded):
    """ expand meta_datas to one level

    Args:
        meta_datas (dict/list): maybe in nested format

    Returns:
        list: expanded list in one level

    Examples:
        >>> meta_datas = [
                [
                    dict1,
                    dict2
                ],
                dict3
            ]
        >>> meta_datas_expanded = []
        >>> __expand_meta_datas(meta_datas, meta_datas_expanded)
        >>> print(meta_datas_expanded)
            [dict1, dict2, dict3]

    """
    if isinstance(meta_datas, dict):
        meta_datas_expanded.append(meta_datas)
    elif isinstance(meta_datas, list):
        for meta_data in meta_datas:
            __expand_meta_datas(meta_data, meta_datas_expanded)