code: def make_secure_channel(credentials, user_agent, host, extra_options=()):
      
      target = "%s:%d" % (host, http_client.HTTPS_PORT)
      http_request = google.auth.transport.requests.Request()
  
      user_agent_option = ("grpc.primary_user_agent", user_agent)
      options = (user_agent_option,) + extra_options
      return google.auth.transport.grpc.secure_authorized_channel(
          credentials, http_request, target, options=options
      )
docs: Makes a secure channel for an RPC service.
  
      Uses / depends on gRPC.
  
      :type credentials: :class:`google.auth.credentials.Credentials`
      :param credentials: The OAuth2 Credentials to use for creating
                          access tokens.
  
      :type user_agent: str
      :param user_agent: The user agent to be used with API requests.
  
      :type host: str
      :param host: The host for the service.
  
      :type extra_options: tuple
      :param extra_options: (Optional) Extra gRPC options used when creating the
                            channel.
  
      :rtype: :class:`grpc._channel.Channel`
      :returns: gRPC secure channel with credentials attached.