code: def _set_proxy_headers(self, url, headers=None):
          
          headers_ = {'Accept': '*/*'}
  
          netloc = parse_url(url).netloc
          if netloc:
              headers_['Host'] = netloc
  
          if headers:
              headers_.update(headers)
          return headers_
docs: Sets headers needed by proxies: specifically, the Accept and Host
          headers. Only sets headers not provided by the user.