anchor.diff:          var OpenStreetMap_DE = L.tileLayer('http://{s}.tile.openstreetmap.de/tiles/osmde/{z}/{x}/{y}.png', {
               maxZoom: 19,
               attribution: '&copy; <a href="http://www.openstreetmap.org/copyright">OpenStreetMap</a>'
  -        }).addTo(mymap);
  +        });
  +        OpenStreetMap_DE.addTo(mymap);
   
           //draw markers
           var markers = L.markerClusterGroup();
           locations.map(markerForEvent).forEach(function (marker) {
               markers.addLayer(marker);
  -        })
  +        });
   
           mymap.addLayer(markers);
   
  
positive.code: 
  <% content_for :scripts do %>
  <script type="text/javascript">
      var mymap = null;
      var sicily_coords = [37.5579, 14.1368];
      var zoom = 7;
  
negative.code:         var index = indexForEvent(ev);
          var options = {
              icon: iconForEvent(ev)
          };
  
          return L.marker([
              coordinates[0], coordinates[1]
  