code: func (o *OAuthSession) Unsave(v Voter, category string) error {
  	// Build form for POST request.
  	form := url.Values{
  		"id":       {v.voteID()},
  		"category": {category},
  	}
  	var u interface{}
  
  	err := o.postBody("https://oauth.reddit.com/api/unsave", form, u)
  	if err != nil {
  		return err
  	}
  	return nil
  }
docs: // Unsave saves a link or comment using OAuth.