import * as Leaflet from "leaflet"; declare module "leaflet" { interface OpacityOptions extends Leaflet.ControlOptions { collapsed?: boolean label?: string | null } namespace Control { class Opacity extends Leaflet.Control { constructor( options?: OpacityOptions ) } } namespace control { function opacity(overlays: { [key: string]: L.Layer }, options: OpacityOptions): L.Control.Opacity } }