advanced queiring

public static  string GetBooksByAgeRestriction(BookShopContext context,string command)
        {

           int restriction =(int)(AgeRestriction)Enum.Parse(typeof(AgeRestriction),command.ToLower(),ignoreCase:true);

              var bookTitles = context.Books
                .Where(x =>x.AgeRestriction==(AgeRestriction)restriction)
                .Select(x=>x.Title)
                .OrderBy(x=>x).ToArray();
            string output = string.Join(Environment.NewLine, bookTitles);
            return output;

        }