code: function prettyUrl(file) {
    file.extname = ".html";
  
    if (file.basename !== "index") {
      file.dirname = path.join(file.dirname, file.basename);
      file.basename = "index";
    }
  
    return file;
  }
docs: Generate pretty URLs for files piped through this method.
  
  @see `gulp-rename` for more information
  
  @param {Object} file Object containing file path information
  @return Modified file path object