using System;

using System.Collections.Generic;

​

public class Program

{

    public static void Main()

    {

        foreach (var ComposerName in GetCompGenius()) // (1)

            Console.WriteLine(ComposerName);

    }

​

    static IEnumerable<string> GetCompGenius()        // (2)

    {

        List<Composer> Lst = new List<Composer>()     // (3)

        {

            new Composer() {Name = "Wolfgang Amadeus Mozart", Genius = true},

            new Composer() {Genius = true},

            new Composer() {Name = "Maurice Ravel", Genius = false},

            new Composer() {Name = "Antonio Salieri", Genius = false} ,

        };

        foreach (var composer in Lst)                 // (4)

        {   // NEW

            if(composer is Composer {Name: string name} composer1 && 

                    composer1.Genius.Equals(true))

                yield return composer1.Name;

        }

    }

​

    public class Composer                             // (5)

    {

        public string Name { get; set; }

        public bool Genius { get; set; }

    }

}