code: function renderGraph(componentDirectory, sortedComponents) {
    let dot = [
      '// This graph shows all dependencies for this loader.',
      '// You might find http://www.webgraphviz.com/ useful!',
      '',
      'digraph G {',
    ];
  
    for (let component of sortedComponents) {
      dot.push(util.format('  "%s"', component));
      let def = componentDirectory[component] || {};
      for (let dep of def.requires || []) {
        dot.push(util.format('  "%s" -> "%s" [dir=back]', dep, component));
      }
    }
    dot.push('}');
  
    return dot.join('\n');
  }
docs: Render componentDirectory to dot format for graphviz given a
  topologically sorted list of components