What’s New in C# 7.0(blogs.msdn.microsoft.com)

  public static IList<Ephraimite> FindEphraimitesToKill(IList<Ephraimite> ephraimites)
  {
      var ephraimitesToKill = new List<Ephraimite>();
      foreach (var ephraimite in ephraimites)         
          if (ephraimite.Speak("shibboleth") == "sibboleth")            
              ephraimitesToKill.Add(ephraimite);                    
      return ephraimitesToKill;
  }

  public static IList<Ephraimite> FindEphraimitesToKill(IList<Ephraimite> ephraimites)
  {
      return ephraimites.Where(e => e.Speak("shibboleth") == "sibboleth").ToList()
  }

    public SomeMethod(bool b) -> (string name, int id) { ... }

        IEnumerable<Student> GetStudents(SqlCommand cmd)
	{
		var rdr = cmd.ExecuteReader();
		var memo = new Dictionary<int, Student.Completion>();

		while(rdr.Read())
		{
			Student.Completion completion; //this declaration will be unnecessary in C# 7
			
			if(!memo.TryGetValue(rdr.GetInt32("student_id"), out completion))
				memo.Add(new Student(rdr, out completion).ID, completion);
			
			completion.AddCourse(rdr); //completion is *guaranteed* to be non-null
		}
		
		return from kv in memo select kv.Value.Student;
	}

    memo.Add(new Student(rdr, out completion).ID, completion);

     return from kv in memo select kv.Value.Student //`Value` is an instance of Student.Completion

        sealed class Student
	{
		public int ID { get; } //this is a readonly property, meaning it can only be modified in a cstor
		public FullName { get; } //readonly property

		private List<Course> courses = new List<Courses>(); 

                public IEnumerable<Course> Courses => from c in courses select c;
		
		public Student(IDataReader rdr,  out Completion completion)
		{
			ID = rdr.GetInt32("student_id");
			Fullname =  rdr.GetString("fullname");
			
			completion = new Completion(this);
		}
		
		public sealed class Completion
		{
			public Student Student { get; } //readonly property.
			
			public Completion(Student student)
			{
				this.Student =  student;
			}
			
			public void AddCourse(IDataReader rdr)
			{
				if(rdr.GetInt32("student_id) == Student.ID)
					student.courses.Add(new Course(rdr));
			}
		}
	}