code: func (q *Query) BelongsToAs(model interface{}, as string) *Query {
  	m := &Model{Value: model}
  	q.Where(fmt.Sprintf("%s = ?", as), m.ID())
  	return q
  }
docs: // BelongsToAs adds a "where" clause based on the "ID" of the
  // "model" passed into it, using an alias.