removeData: ->

  emitChange: -> @emit(CHANGE_EVENT)
  addChangeListener: (callback) -> @addListener(CHANGE_EVENT, callback)
  remove: -> @removeListener(CHANGE_EVENT, @removeData)
  emitItemChange: (itemForm) -> @emit(CHANGE_ITEM_EVENT, itemForm)
  addItemChangeListener: (callback) -> @addListener(CHANGE_ITEM_EVENT, callback)