def METHOD_NAME(path):
    suffix_count = len(path.suffixes)
    if suffix_count and len(path.suffixes[-1]) == 4:
        extension = path.suffixes[-1].lower()
    elif path.suffixes[-1].lower() == '.gz' and suffix_count >= 2 and len(path.suffixes[-2]) == 4:
        extension = ''.join(path.suffixes[-2:]).lower()
    else:
        extension = ''
    return extension