text: var osmUrl='https://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png';
  var osmAttrib='Map data © <a href="http://osm.org/copyright">OpenStreetMap</a> contributors';
  var osm = new L.TileLayer(osmUrl, {
      attribution: osmAttrib,
      detectRetina: true
  });
  
  var token = 'pk.eyJ1IjoiZG9tb3JpdHoiLCJhIjoieENoTEhXUSJ9.kjCosRk1pmnOqTvfsjmgIg';
  var mapboxUrl = 'https://api.tiles.mapbox.com/v4/mapbox.streets/{z}/{x}/{y}@2x.png?access_token=' + token;
  var mapboxAttrib = 'Map data © <a href="http://osm.org/copyright">OpenStreetMap</a> contributors. Tiles from <a href="https://www.mapbox.com">Mapbox</a>.';
  var mapbox = new L.TileLayer(mapboxUrl, {
    attribution: mapboxAttrib
  });
  
  var map = new L.Map('map', {
      layers: [mapbox],
      center: [51.505, -0.09],
      zoom: 10,
      zoomControl: true
  });
  
  // add location control to global name space for testing only
  // on a production site, omit the "lc = "!
  lc = L.control.locate({
      strings: {
          title: "Show me where I am, yo!"
      }
  }).addTo(map);
  