<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def maybe_download(url, filename):
 """Download the data from Yann's website, unless it's already here."""

  if not os.path.exists(WORK_DIRECTORY):
    os.mkdir(WORK_DIRECTORY)
  filepath = os.path.join(WORK_DIRECTORY, filename)
  if not os.path.exists(filepath):
    filepath, _ = request.urlretrieve(url + filename, filepath)
    statinfo = os.stat(filepath)
    print('Successfully downloaded', filename, statinfo.st_size, 'bytes.')
  return filepath