code: func (api *Client) GetChannelHistoryContext(ctx context.Context, channelID string, params HistoryParameters) (*History, error) {
  	values := url.Values{
  		"token":   {api.token},
  		"channel": {channelID},
  	}
  	if params.Latest != DEFAULT_HISTORY_LATEST {
  		values.Add("latest", params.Latest)
  	}
  	if params.Oldest != DEFAULT_HISTORY_OLDEST {
  		values.Add("oldest", params.Oldest)
  	}
  	if params.Count != DEFAULT_HISTORY_COUNT {
  		values.Add("count", strconv.Itoa(params.Count))
  	}
  	if params.Inclusive != DEFAULT_HISTORY_INCLUSIVE {
  		if params.Inclusive {
  			values.Add("inclusive", "1")
  		} else {
  			values.Add("inclusive", "0")
  		}
  	}
  
  	if params.Unreads != DEFAULT_HISTORY_UNREADS {
  		if params.Unreads {
  			values.Add("unreads", "1")
  		} else {
  			values.Add("unreads", "0")
  		}
  	}
  
  	response, err := api.channelRequest(ctx, "channels.history", values)
  	if err != nil {
  		return nil, err
  	}
  	return &response.History, nil
  }
docs: // GetChannelHistoryContext retrieves the channel history with a custom context
  // see https://api.slack.com/methods/channels.history