A minimal D3 example demonstrates a single SVG circle moving across a 500-by-500 canvas in a three-step animated sequence. The circle initially appears at coordinates (50,50), then transitions horizontally to (150,50), drops vertically to (150,200), and finally returns to its starting x-position. The animation uses chained `transition()` calls with a 1500-millisecond duration per step. The code builds the SVG scene using `d3.select("body").append("svg")` and `attr()`, relying on D3 v3 loaded from the d3js.org CDN within a plain HTML page.