public static class LinqExtension	{		public static T MaxBy
     
      (this IEnumerable
      
        en, Func
       
         evaluate) where TR : IComparable		{			return en.Select(t => new Tuple
        
         (t, evaluate(t)))				.Aggregate((max, next) => next.Item2.CompareTo(max.Item2) > 0 ? next : max).Item1;		}		public static T MinBy
         
          (this IEnumerable
          
            en, Func
           
             evaluate) where TR : IComparable { return en.Select(t => new Tuple
            
             (t, evaluate(t))) .Aggregate((max, next) => next.Item2.CompareTo(max.Item2) < 0 ? next : max).Item1; } }