text: // topoJSON data to draw country outlines
  // Source: Natural Earth 1:50m Cultural Vectors, Admin 0 - Countries
  const mapPath = "./naturalEarth50TopoJSON.json";
  
  // 2017 world population data. Source: https://databank.worldbank.org
  const popPath = "./worldPopulation.csv";
  
  // Setup
  const svgWidth = 1000;
  const svgHeight = 700;
  const scale = svgWidth / (2 * Math.PI);
  
  const svg = d3.select("#map")
      .append("svg")
      .attr("width", svgWidth)
      .attr("height", svgHeight);
  
  const projection = d3.geoMercator()
      .scale(scale)
      .translate([svgWidth / 2, svgHeight / 2])
      .center([0, 20]);
  
  const path = d3.geoPath()
      .projection(projection);
  
  // Create a group to hold the countries
  const g = svg.append("g");
  
  // Create requests to retrieve JSON topography data and CSV population data
  const getJSONData = d3.json(mapPath);
  const getCSVData = d3.csv(popPath);
  
  Promise.all([getJSONData, getCSVData]).then(function(values) {
    const json = values[0];
    const population = values[1];
  
    // Find the max and min population values in the data to better understand it
  
  
  
  });
  
  /*
  Often with data visualizations, you'll want to size or color items based on the
  underlying values in the dataset. For example, in a bar chart, you want the height
  of each bar to tie to the value it's showing. In your map, you're going to color
  the country based on how many people live there.
  
  D3 scales provide the functionality to do this. But before getting into scales,
  you're going to want to understand your data. The data type (discrete or
  continuous), how they're distributed, and what you're trying to visualize will
  all help to determine the type of scale that is most appropriate to use.
  
  When D3 imported the CSV data (available in `population.Population`), it loaded
  the figures as strings. You need to first map them into an array as numbers before
  you can analyze them.
  
  Using the `const` keyword, declare a variable named `popArray`, then apply the
  `.map()` method on `population`. Use an arrow callback function with one parameter
  `d` that returns the population figures changed to numbers (you can access them
  with `d.Population`). A shortcut to cast a string to a number in JavaScript is to
  add a `+` in front of the string, for example `+numAsString`.
  */
  