code: func (api *Client) CloseConversationContext(ctx context.Context, channelID string) (noOp bool, alreadyClosed bool, err error) {
  	values := url.Values{
  		"token":   {api.token},
  		"channel": {channelID},
  	}
  	response := struct {
  		SlackResponse
  		NoOp          bool `json:"no_op"`
  		AlreadyClosed bool `json:"already_closed"`
  	}{}
  
  	err = api.postMethod(ctx, "conversations.close", values, &response)
  	if err != nil {
  		return false, false, err
  	}
  
  	return response.NoOp, response.AlreadyClosed, response.Err()
  }
docs: // CloseConversationContext closes a direct message or multi-person direct message with a custom context