get_providers           Fetch leaflet providers from Leaflet.js.
providers_default       Return default providers, providers_details,
                        version, and HTML Dependency.
providers_loaded        Return currently loaded providers,
                        providers_details, version, and HTML
                        Dependency.
use_providers           Use a custom 'leaflet_providers' object, e.g.
                        providers data fetched with get_providers, with
                        the 'leaflet' package.
