code: def _get_download_or_cache(filename, data_home=None,
                             url=SESAR_RRLYRAE_URL,
                             force_download=False):
      
      # Import here so astroML is not required at package level
      from astroML.datasets.tools import get_data_home
  
      if data_home is None:
          data_home = get_data_home(data_home)
      data_home = os.path.join(data_home, 'Sesar2010')
      if not os.path.exists(data_home):
          os.makedirs(data_home)
  
      src_url = SESAR_RRLYRAE_URL + filename
      save_loc = os.path.join(data_home, filename)
  
      if force_download or not os.path.exists(save_loc):
          fhandle = urlopen(src_url)
          with open(save_loc, 'wb') as cache:
              cache.write(fhandle.read())
      return save_loc
docs: Private utility to download and/or load data from disk cache.