How to use the wordfreq.config.DB_FILENAME function in wordfreq

"""
    from tempfile import TemporaryDirectory

    if upload_path is None:
        upload_path = config.UPLOAD_PATH
    
    with TemporaryDirectory('.wordfreq') as build_dir:
        version_dir = os.path.join(build_dir, config.MINOR_VERSION)
        os.makedirs(version_dir)

        source_filename = os.path.join(version_dir, 'wordfreq-data.tar.gz')
        logger.info("Creating %s" % source_filename)
        with tarfile.open(source_filename, 'w:gz') as tarf:
            tarf.add(config.RAW_DATA_DIR)

        logger.info("Copying database file %s" % config.DB_FILENAME)
        subprocess.call([
            '/bin/cp',
            config.DB_FILENAME,
            version_dir
        ])

        logger.info("Uploading to %s" % upload_path)
        subprocess.call([
            '/usr/bin/rsync',
            '-avz',
            version_dir,
            upload_path
        ])

from functools32 import lru_cache
    PY2 = True
else:
    from functools import lru_cache
    PY2 = False

SQLITE_ERROR_TEXT = """
Couldn't open the wordlist database.
You may need to run wordfreq's setup.py script.

I was expecting to find the database at:

    %(path)s

This can be configured by setting the WORDFREQ_DATA environment variable.
""" % {'path': DB_FILENAME}

try:
    if PY2:
        CONN = sqlite3.connect(DB_FILENAME)
    else:
        CONN = sqlite3.connect(DB_FILENAME, check_same_thread=False)
except sqlite3.OperationalError:
    raise IOError(SQLITE_ERROR_TEXT)


@lru_cache(maxsize=CACHE_SIZE)
def word_frequency(word, lang, wordlist='multi', offset=0.):
    """
    Get the frequency of `word` in the language with code `lang`, from the
    specified `wordlist`.

if upload_path is None:
        upload_path = config.UPLOAD_PATH
    
    with TemporaryDirectory('.wordfreq') as build_dir:
        version_dir = os.path.join(build_dir, config.MINOR_VERSION)
        os.makedirs(version_dir)

        source_filename = os.path.join(version_dir, 'wordfreq-data.tar.gz')
        logger.info("Creating %s" % source_filename)
        with tarfile.open(source_filename, 'w:gz') as tarf:
            tarf.add(config.RAW_DATA_DIR)

        logger.info("Copying database file %s" % config.DB_FILENAME)
        subprocess.call([
            '/bin/cp',
            config.DB_FILENAME,
            version_dir
        ])

        logger.info("Uploading to %s" % upload_path)
        subprocess.call([
            '/usr/bin/rsync',
            '-avz',
            version_dir,
            upload_path
        ])

SQLITE_ERROR_TEXT = """
Couldn't open the wordlist database.
You may need to run wordfreq's setup.py script.

I was expecting to find the database at:

    %(path)s

This can be configured by setting the WORDFREQ_DATA environment variable.
""" % {'path': DB_FILENAME}

try:
    if PY2:
        CONN = sqlite3.connect(DB_FILENAME)
    else:
        CONN = sqlite3.connect(DB_FILENAME, check_same_thread=False)
except sqlite3.OperationalError:
    raise IOError(SQLITE_ERROR_TEXT)


@lru_cache(maxsize=CACHE_SIZE)
def word_frequency(word, lang, wordlist='multi', offset=0.):
    """
    Get the frequency of `word` in the language with code `lang`, from the
    specified `wordlist`.

    The offset gets added to all values, to monotonically account for the
    fact that we have not observed all possible words.
    """
    c = CONN.cursor()
    c.execute("SELECT freq from words where word=? and lang=? and wordlist=?",
              (standardize_word(word), lang, wordlist))

def download_db(url=None, dest_filename=None):
    """
    Download the database itself, so we don't have to build it.
    """
    if url is None:
        url = config.DB_URL

    if dest_filename is None:
        dest_filename = config.DB_FILENAME

    ensure_dir_exists(dest_filename)
    download(url, dest_filename)