code: def _FetchServerCertificate(self):
      
      # Certificate is loaded and still valid.
      if self.server_certificate:
        return True
  
      response = self.http_manager.OpenServerEndpoint(
          "server.pem", verify_cb=self.VerifyServerPEM)
  
      if response.Success():
        self.server_certificate = response.data
        return True
  
      # We failed to fetch the cert, switch to slow poll mode.
      self.timer.SlowPoll()
      return False
docs: Attempts to fetch the server cert.
  
      Returns:
        True if we succeed.