text: 
  var map = new maptalks.Map('map', {
    center: [-0.113049,51.49856],
    zoom: 10,
    baseLayer: new maptalks.TileLayer('base', {
      urlTemplate: '$(urlTemplate)',
      subdomains: $(subdomains),
      attribution: '$(attribution)'
    })
  });
  
  var layer = new maptalks.VectorLayer('vector').addTo(map);
  
  var line = new maptalks.LineString(
    [
      map.getCenter().sub(0.1, 0),
      map.getCenter().add(0.1, 0),
      map.getCenter().add(0.1, -0.1)
    ],
    {
      arrowStyle : 'classic', // we only have one arrow style now
      arrowPlacement : 'vertex-firstlast', //vertex-first, vertex-last, vertex-firstlast, point
      symbol:{
        'lineColor' : '#1bbc9b',
        'lineWidth' : 8
      }
    }
  ).addTo(layer);
  