text: //add console.log to check to see if our code is working
  console.log("working");
  
  // Retrieve the earthquake GeoJSON data.
  d3.json("https://earthquake.usgs.gov/earthquakes/feed/v1.0/summary/all_week.geojson").then(function(data) {
    // Creating a GeoJSON layer with the retrieved data.
    L.geoJSON(data).addTo(map);
  });
  
  // We create the dark view tile layer that will be an option for our map.
  let streets = L.tileLayer('https://api.mapbox.com/styles/v1/mapbox/streets-v11/tiles/{z}/{x}/{y}?access_token={accessToken}', {
  attribution: 'Map data © <a href="https://www.openstreetmap.org/">OpenStreetMap</a> contributors, <a href="https://creativecommons.org/licenses/by-sa/2.0/">CC-BY-SA</a>, Imagery (c) <a href="https://www.mapbox.com/">Mapbox</a>',
      maxZoom: 18,
      accessToken: API_KEY
  });
  
  // We create the tile layer that will be the background of our map.
  let satelliteStreets = L.tileLayer('https://api.mapbox.com/styles/v1/mapbox/satellite-streets-v10/tiles/{z}/{x}/{y}?access_token={accessToken}', {
      attribution: 'Map data &copy; <a href="https://www.openstreetmap.org/">OpenStreetMap</a> contributors, <a href="https://creativecommons.org/licenses/by-sa/2.0/">CC-BY-SA</a>, Imagery © <a href="https://www.mapbox.com/">Mapbox</a>',
      maxZoom: 18,
      accessToken: API_KEY
  });
  
  // Create a base layer that holds both maps.
  let baseMaps = {
    "Streets": streets,
    "Satellite Streets": satelliteStreets
  };
  
  // Create the map object with center, zoom level and default layer.
  let map = L.map('mapid', {
    center: [39.5, -98.5],
    zoom: 3,
    layers: [streets]
  })
  
  // Pass our map layers into our layers control and add the layers control to the map.
  L.control.layers(baseMaps).addTo(map);