anchor.diff:        return this
       }
       ConfSite.prototype.setCurrentConference = function setCurrentConference(conf_label) {
  -      this.conference_current_index = this.conferences.indexOf(this.getConference(conf_label, 'with_key'))
  +      this._conference_current_index = conf_label
         this.initializeMainPages()
         return this
       }
       ConfSite.prototype.setPrevConference = function setPrevConference(conf_label) {
  -      this.conference_prev_index = this.conferences.indexOf(this.getConference(conf_label, 'with_key'))
  +      this._conference_prev_index = conf_label
         return this
       }
       ConfSite.prototype.setNextConference = function setNextConference(conf_label) {
  -      this.conference_next_index = this.conferences.indexOf(this.getConference(conf_label, 'with_key'))
  +      this._conference_next_index = conf_label
         return this
       }
       ConfSite.prototype.addSupporterLevel = function addSupporterLevel(supporter_level) {
  
positive.code:       Page.call(self, { name: name, url: url })
        self.was_initialized = false
        self.logo               = ''
        self.conferences        = []
        self.conference_current_index = NaN
        self.conference_prev_index = NaN
        self.conference_next_index = NaN
        self.supporter_levels   = []
        self.supporters         = []
      }
      ConfSite.prototype = Object.create(Page.prototype)
      ConfSite.prototype.constructor = ConfSite
  
negative.code:       return this
      }
      ConfSite.prototype.addConference = function addConference(conf_label, conference) {
        this.conferences[conf_label] = conference
        return this
      }
      ConfSite.prototype.removeConference = function removeConference(conf_label) {
  