def check_archive_formats(formats):
    """Returns the first format from the 'format' list that is unknown.

    If all formats are known, returns None
    """
    for format in formats:
        if format not in ARCHIVE_FORMATS:
            return format
    return None
Returns the first format from the 'format' list that is unknown.

    If all formats are known, returns None
    
product/gradle-plugin/src/main/python/setuptools/_distutils/archive_util.py