code: func (r *Result) Scalar() (Scalar, error) {
  	if r.Err != nil {
  		return Scalar{}, r.Err
  	}
  	v, ok := r.Value.(Scalar)
  	if !ok {
  		return Scalar{}, errors.New("query result is not a Scalar")
  	}
  	return v, nil
  }
docs: // Scalar returns a Scalar value. An error is returned if
  // the result was an error or the result value is not a Scalar.