This example visualizes a Swagger API specification as a Sankey diagram, mapping endpoints like `/pet/{petId}` through HTTP methods such as post, get, put, and delete, and then to response codes like 200, 400, 404, and 405. The diagram also traces data fields like petId and status from operation names such as "update a pet" into the resource layer. Built with D3.js and the `d3.sankey` layout, the SVG uses draggable nodes and semi-transparent link paths to show flow, with `d3.behavior.drag` enabling interactive repositioning of nodes. The rendered graph is static without animation.