code: func (call *LeaveGroupCall) Do() (*BasicResponse, error) {
  	endpoint := fmt.Sprintf(APIEndpointLeaveGroup, call.groupID)
  	res, err := call.c.post(call.ctx, endpoint, nil)
  	if err != nil {
  		return nil, err
  	}
  	defer closeResponse(res)
  	return decodeToBasicResponse(res)
  }
docs: // Do method