code: function(layerModel, leafletLayer, leafletMap) {
      this.leafletLayer = leafletLayer;
      this.leafletMap = leafletMap;
      this.model = layerModel;
  
      this.setModel(layerModel);
  
      this.type = layerModel.get('type') || layerModel.get('kind');
      this.type = this.type.toLowerCase();
    }
docs: base layer for all leaflet layers