This example generates a geometric composition inspired by Sol LeWitt using D3.js. It shows a grid of intersecting horizontal and vertical bars that are visible only within two overlapping circular regions. The artwork uses SVG masks to reveal the bar patterns, with one mask showing the horizontal bars in a circle and the other showing the vertical bars in an inverse circle. The code creates 100 bars in each direction and applies the masks via `svg.append('mask')` and the `attr('mask', ...)` method.