import zipfile


def un_zip(zip_file, uzip_folder=None):
    """Uncompression .zip file
    
    Args:
        zip_files: str, zip_file should be file path;
        uzip_folder: str, uncompression files name.
    Return:
        uzip_folder: str, uncompression files name.
    """
    assert zip_file[-4:]==".zip", '`zip_file` should be `xxx.zip`'
    if uzip_folder is None:
        uzip_folder = zip_file[:-4]
    with zipfile.ZipFile(zip_file, 'r') as z:
        names = z.namelist()
        for name in names:
            z.extract(name, uzip_folder)
    return uzip_folder