code: function destRelative(item, options) {
    if (typeof item.relative !== 'string') {
      throw new TypeError('expected item.relative to be a string');
    }
  
    var context = this || options.data.root;
    var dest = get(context, 'app.options.dest');
    var dataDest = get(item, 'data.dest');
    var folder = '';
  
    if (dest && dataDest) {
      folder = path.relative(dest, dataDest);
    }
    return path.join(folder, item.relative);
  }
docs: Utils