getSort(listId, swimlaneId, top) {
    if (!_.isBoolean(top)) {
      top = true;
    }
    if (!listId) {
      listId = this.listId;
    }
    if (!swimlaneId) {
      swimlaneId = this.swimlaneId;
    }
    const selector = {
      listId: listId,
      swimlaneId: swimlaneId,
      archived: false,
    };
    const sorting = top ? 1 : -1;
    const card = ReactiveCache.getCard(selector, { sort: { sort: sorting } }, true);
    let ret = null
    if (card) {
      ret = card.sort;
    }
    return ret;
  }
returns the sort number of a list
@param listId a list id
@param swimlaneId a swimlane id
top sorting of the card at the top if true, or from the bottom if false