docs: function mustPreserveItems(state) {
    let plugins = state.plugins
    if (cachedPreserveItemsPlugins != plugins) {
      cachedPreserveItems = false
      cachedPreserveItemsPlugins = plugins
      for (let i = 0; i < plugins.length; i++) if (plugins[i].spec.historyPreserveItems) {
        cachedPreserveItems = true
        break
      }
    }
    return cachedPreserveItems
  }