code: def get_summary(section, domain, uri, use_cache):
      
      logging.debug('Checking for a cached summary file')
  
      cachefile = "{section}_{domain}_assembly_summary.txt".format(section=section, domain=domain)
      full_cachefile = os.path.join(CACHE_DIR, cachefile)
      if use_cache and os.path.exists(full_cachefile) and \
         datetime.utcnow() - datetime.fromtimestamp(os.path.getmtime(full_cachefile)) < timedelta(days=1):
          logging.info('Using cached summary.')
          with codecs.open(full_cachefile, 'r', encoding='utf-8') as fh:
              return StringIO(fh.read())
  
      logging.debug('Downloading summary for %r/%r uri: %r', section, domain, uri)
      url = '{uri}/{section}/{domain}/assembly_summary.txt'.format(
          section=section, domain=domain, uri=uri)
      req = requests.get(url)
  
      if use_cache:
          try:
              os.makedirs(CACHE_DIR)
          except OSError as err:
              # Errno 17 is "file exists", ignore that, otherwise re-raise
              if err.errno != 17:
                  raise
  
          with codecs.open(full_cachefile, 'w', encoding='utf-8') as fh:
              fh.write(req.text)
  
      return StringIO(req.text)
docs: Get the assembly_summary.txt file from NCBI and return a StringIO object for it.