code: def load_data_file(fname, directory=None, force_download=False):
      
      _url_root = 'http://github.com/vispy/demo-data/raw/master/'
      url = _url_root + fname
      if directory is None:
          directory = config['data_path']
          if directory is None:
              raise ValueError('config["data_path"] is not defined, '
                               'so directory must be supplied')
  
      fname = op.join(directory, op.normcase(fname))  # convert to native
      if op.isfile(fname):
          if not force_download:  # we're done
              return fname
          if isinstance(force_download, string_types):
              ntime = time.strptime(force_download, '%Y-%m-%d')
              ftime = time.gmtime(op.getctime(fname))
              if ftime >= ntime:
                  return fname
              else:
                  print('File older than %s, updating...' % force_download)
      if not op.isdir(op.dirname(fname)):
          os.makedirs(op.abspath(op.dirname(fname)))
      # let's go get the file
      _fetch_file(url, fname)
      return fname
docs: Get a standard vispy demo data file
  
      Parameters
      ----------
      fname : str
          The filename on the remote ``demo-data`` repository to download,
          e.g. ``'molecular_viewer/micelle.npy'``. These correspond to paths
          on ``https://github.com/vispy/demo-data/``.
      directory : str | None
          Directory to use to save the file. By default, the vispy
          configuration directory is used.
      force_download : bool | str
          If True, the file will be downloaded even if a local copy exists
          (and this copy will be overwritten). Can also be a YYYY-MM-DD date
          to ensure a file is up-to-date (modified date of a file on disk,
          if present, is checked).
  
      Returns
      -------
      fname : str
          The path to the file on the local system.