anchor.diff:  
     // private methods that modify map state
   
  -  _resetView(center, zoom, preserveMapOffset, afterZoomAnim) {
  +  _resetView(center, zoom, [preserveMapOffset=false, afterZoomAnim=false]) {
   
       var zoomChanged = (this._zoom != zoom);
   
  
positive.code: 
      this.callInitHooks();
  
      this._addLayers(options.layers);
    }
  
  
    // public methods that modify map state
  
    // replaced by animation-powered implementation in Map.PanAnimation.js
    setView(center, zoom) {
      zoom = zoom == null ? this.getZoom() : zoom;
      this._resetView(L.latLng(center), this._limitZoom(zoom));
      return this;
    }
  
    setZoom(zoom, options) {
      if (!this._loaded) {
  
negative.code: 
    // map initialization methods
  
    var _container;
  
    _initContainer(id) {
      var container = this._container = L.DomUtil.get(id);
  
      if (!container) {
        throw new Exception('Map container not found.');
      } else if (container._leaflet) {
        throw new Exception('Map container is already initialized.');
      }
  
      container._leaflet = true;
  