text: import Map from 'ol/Map.js';
  import View from 'ol/View.js';
  import OLGoogleMaps from 'olgm/OLGoogleMaps.js';
  import GoogleLayer from 'olgm/layer/Google.js';
  import {defaults as defaultInteractions} from 'olgm/interaction.js';
  
  
  const center = [-7908084, 6177492];
  
  const regularLayer = new GoogleLayer({
    visible: false
  });
  
  const themedLayer = new GoogleLayer({
    styles: [{
      'stylers': [{
        'saturation': -100
      }, {
        'gamma': 2.25
      }]
    }]
  });
  
  const map = new Map({
    // use OL3-Google-Maps recommended default interactions
    interactions: defaultInteractions(),
    layers: [
      regularLayer,
      themedLayer
    ],
    target: 'map',
    view: new View({
      center: center,
      zoom: 12
    })
  });
  
  const olGM = new OLGoogleMaps({map: map}); // map is the Map instance
  olGM.activate();
  
  document.getElementById('toggle').addEventListener('click', function() {
    regularLayer.setVisible(!regularLayer.getVisible());
    themedLayer.setVisible(!themedLayer.getVisible());
  });
  