code: func (p *Partial) SliceOfLength(length int) (a []*Partial, err error) {
  	err = p.Unmarshal(&a)
  	if err != nil {
  		return
  	}
  
  	if len(a) != length {
  		err = errors.New("Invalid array length")
  	}
  
  	return
  }
docs: // SliceOfLength is a helper method to unmarshal a JSON Array with specified length.