This example visualizes a hierarchical tree of function calls from a C codebase, with the root “main” branching into manager functions and their nested subroutines. The data, loaded from a JSON file, is displayed using D3 v5’s `tree` layout and `hierarchy` function, with nodes connected by `linkHorizontal` paths. Panning and zooming are enabled via `d3.zoom`, and the SVG text labels carry file paths and function names. The visual uses a teal stroke and serif typography to present the call graph clearly.