code: function platoExcludes() {
      var excludes = '';
      excludeFileset.forEach(function (file) {
          if (isDirectory(file)) {
              excludes += file.replace(/\//g, '\/');
          } else {
              excludes += file;
          }
          excludes += '|';
      });
  
      if (excludes !== '') {
          return new RegExp(excludes.slice(0, -1));
      } else {
          return null;
      }
  }
docs: Plato uses a regular expression to exclude files so turn the list of exclude files into a properly formatted, pipe delimited list of files. If there are no filesets to exclude then `null` is returned.