code: def _Initialize(self, http, url):
          
          self.EnsureUninitialized()
          if self.http is None:
              self.__http = http or http_wrapper.GetHttp()
          self.__url = url
docs: Initialize this download by setting self.http and self.url.
  
          We want the user to be able to override self.http by having set
          the value in the constructor; in that case, we ignore the provided
          http.
  
          Args:
            http: An httplib2.Http instance or None.
            url: The url for this transfer.
  
          Returns:
            None. Initializes self.