anchor.diff:          .file villains.module.ts
           .file villains-routing.module.ts
         .file app.component.ts|html|css|spec.ts
  -    .file app.module.ts
  -    .file app-routing.module.ts
  +      .file app.module.ts
  +      .file app-routing.module.ts
       .file main.ts
       .file index.html
       .file ...
  
positive.code: 
  a(id='file-tree')
  :marked
    Folder and File Structure
  
  .filetree
    .file src
    .children
      .file app
      .children
  
negative.code: 
  .s-rule.do
    :marked
      **Do** create an Angular module in the app's root folder (e.g., in `/app`).
  
  .s-why
    :marked
      **Why?** Every app requires at least one root Angular module.
  
  .s-rule.consider
    :marked
  