This piece reproduces a Sol LeWitt drawing using D3 and SVG renderings. Two sets of 100 thin rectangles are drawn—one horizontal and one vertical—creating a grid-like pattern. Each set of rectangles is masked by a circular region: the horizontal bars use a mask with a central white circle on black, while the vertical bars use an inverse mask with a black circle on white. The result shows a grid within a circular window, with the horizontal and vertical lines swapping visibility inside and outside the circle. The code uses `d3.select`, `d3.range`, `svg.append`, and `.join()` to build the SVG elements and masks programmatically.