custom_collection_IEnumerable.cs

  class MyObject
  {
      public int Value { get; set; }
  }

  class MyCollection : IEnumerable<MyObject>
  {
      public IEnumerator<MyObject> GetEnumerator()
      {
          throw new NotImplementedException();
      }

      IEnumerator IEnumerable.GetEnumerator()
      {
          return GetEnumerator();
      }
  }