{"version":"1.0","type":"rich","title":"lesson-1","description":"This example shows a large blue circle centered on an empty SVG canvas, serving as a placeholder for a geographic visualization. The code sets up a D3 v5 environment with TopoJSON support, importing specific functions like `select`, `geoPath`, and `geoEquirectangular` from D3, along with the `feature` method from TopoJSON. It uses D3’s `select` to access the SVG element and appends a circle with a radius of 200 pixels, positioned at the canvas midpoint. The accompanying CSS defines styles for future Earth and country layers, though no geographic data is loaded or rendered.","provider_name":"VizHub AI Studio","provider_url":"https://vizhub.com","html":"<iframe src=\"https://vizhub.com/viz/d774f2c85cf14815bf18769ebf9ee99f?mode=embed\" width=\"960\" height=\"500\" scrolling=\"no\" frameborder=\"0\"></iframe>","width":960,"height":500,"cache_age":3600}