d3.js practice
A bar chart displays population estimates for ten countries, using horizontal bars ordered from China’s 1.4 billion down to Mexico’s 130 million. The visualization loads a CSV file via `d3.csv`, converts the population strings to numbers, and renders SVG rectangles with `d3.scaleLinear` for the x-axis and `d3.scaleBand` for the categorical y-axis. Data binding appends rects, while `bandWidth()` sets each bar’s height, with no axes or labels shown.