anchor.diff:  
       layer = L.layerGroup(markers).addLayer(polyline);
       layer.addTo(map);
  -    markers[markers.length-1].openPopup();
  +
       return layer
     }
   }
  
positive.code: 
      map.removeLayer(markerPathLayer);
      var path = this.information.slice(0, this.currentLocation)
      return this.placePath(path, map, markerPathLayer);
    },
    prev: function(map, markerPathLayer){
      if(this.currentLocation === 1){
  
negative.code: 
      map.removeLayer(markerPathLayer);
      var path = this.information.slice(0, this.currentLocation)
      var layer = this.placePath(path, map, markerPathLayer);
  
      mapMod.animateView(path, map);
      // mapMod.openImage(path, map);
  
      return layer;
    },
    all: function(map, markerPathLayer){
      if(markerPathLayer){
  