code: function plugin (Vue, options = {}) {
    if (plugin.installed) {
      return
    }
    plugin.installed = true
  
    // install components
    Vue.use(ArcgisRestSource, options)
    Vue.use(BingmapsSource, options)
    Vue.use(CircleGeom, options)
    Vue.use(CircleStyle, options)
    Vue.use(ClusterSource, options)
    Vue.use(DrawInteraction, options)
    Vue.use(Feature, options)
    Vue.use(FillStyle, options)
    Vue.use(Geoloc, options)
    Vue.use(Graticule, options)
    Vue.use(GroupLayer, options)
    Vue.use(IconStyle, options)
    Vue.use(ImageLayer, options)
    Vue.use(ImageStaticSource, options)
    Vue.use(ImageWmsSource, options)
    Vue.use(LineStringGeom, options)
    Vue.use(Map, options)
    Vue.use(MapboxSource, options)
    Vue.use(ModifyInteraction, options)
    Vue.use(MultiLineStringGeom, options)
    Vue.use(MultiPointGeom, options)
    Vue.use(MultiPolygonGeom, options)
    Vue.use(OsmSource, options)
    Vue.use(Overlay, options)
    Vue.use(PointGeom, options)
    Vue.use(PolygonGeom, options)
    Vue.use(RegShapeStyle, options)
    Vue.use(SelectInteraction, options)
    Vue.use(SnapInteraction, options)
    Vue.use(SputnikSource, options)
    Vue.use(StamenSource, options)
    Vue.use(StrokeStyle, options)
    Vue.use(StyleBox, options)
    Vue.use(StyleFunc, options)
    Vue.use(TextStyle, options)
    Vue.use(TileLayer, options)
    Vue.use(VectorLayer, options)
    Vue.use(VectorSource, options)
    Vue.use(VectorTileLayer, options)
    Vue.use(VectorTileSource, options)
    Vue.use(WmsSource, options)
    Vue.use(WmtsSource, options)
    Vue.use(XyzSource, options)
  }
docs: Registers all VueLayers components.
  @param {Vue|VueConstructor} Vue
  @param {VueLayersOptions} [options]