Jugando con los Generics

instructions.cs

// Note that you can return any data structure you want, as long it inherits the IEnumerable interface.
UniqueInOrder("AAAABBBCCDAABBB")                     => "ABCDAB"
UniqueInOrder("ABBCcAD")                             => "ABCcAD"
UniqueInOrder("12233")                               => "123"
UniqueInOrder(new List<double> {1.1, 2.2, 2.2, 3.3}) => new List<double> {1.1, 2.2, 3.3}

UniqueInOrder.cs

using System.Collections.Generic;

public static class Kata
{
  public static IEnumerable<T> UniqueInOrder<T>(IEnumerable<T> iterable) 
  {
      List<T> result = new List<T>();
      T pre_item = default(T);
      foreach (T item in iterable) {
         if(!item.Equals(pre_item)){
            result.Add(item);
            pre_item = item;
         }
      } 
      return result;
  }
}