human
I wrote the below code

    def _download(filename, working_directory, url_source):
        def _dlProgress(count, blockSize, totalSize):
            if (totalSize != 0):
                percent = ((float((count * blockSize)) / float(totalSize)) * 100.0)
                sys.stdout.write((('\rDownloading    ' + filename) + ('...%d%%' % percent)))
                sys.stdout.flush()
        if (sys.version_info[0] == 2):
            from urllib import urlretrieve
        else:
            from urllib.request import urlretrieve
        filepath = os.path.join(working_directory, filename)
        urlretrieve((url_source + filename), filepath, reporthook=_dlProgress)
    exists_or_mkdir(working_directory, verbose=False)
    filepath = os.path.join(working_directory, filename)
    if (not os.path.exists(filepath)):
        _download(filename, working_directory, url_source)
        print ()
        statinfo = os.stat(filepath)
        print ('Succesfully    downloaded', filename, statinfo.st_size, 'bytes.')
        if ((not (expected_bytes is None)) and (expected_bytes != statinfo.st_size)):
            raise Exception((('Failed    to    verify    ' + filename) + '.    Can    you    get    to    it    with    a    browser?'))
        if extract:
            if tarfile.is_tarfile(filepath):
                print 'Trying    to    extract    tar    file'
                tarfile.open(filepath, 'r').extractall(working_directory)
                print '...    Success!'
            elif zipfile.is_zipfile(filepath):
                print 'Trying    to    extract    zip    file'
                with zipfile.ZipFile(filepath) as zf:
                    zf.extractall(working_directory)
                print '...    Success!'
            else:
                print 'Unknown    compression_format    only    .tar.gz/.tar.bz2/.tar    and    .zip    supported'
    return filepath

What's a good function header?

Give me a Python code to print ()?
assistant
#Here is Python code to print ()
.

def maybe_download_and_extract(filename, working_directory, url_source, extract=False, expected_bytes=None):