code: func (api *Client) GetPermalinkContext(ctx context.Context, params *PermalinkParameters) (string, error) {
  	values := url.Values{
  		"token":      {api.token},
  		"channel":    {params.Channel},
  		"message_ts": {params.Ts},
  	}
  
  	response := struct {
  		Channel   string `json:"channel"`
  		Permalink string `json:"permalink"`
  		SlackResponse
  	}{}
  	err := api.getMethod(ctx, "chat.getPermalink", values, &response)
  	if err != nil {
  		return "", err
  	}
  	return response.Permalink, response.Err()
  }
docs: // GetPermalinkContext returns the permalink for a message using a custom context.